9+ Easy How to Cook Ribeye in a Cast Iron Skillet Tips


9+ Easy How to Cook Ribeye in a Cast Iron Skillet Tips

The process of searing a ribeye steak within a cast iron skillet represents a technique employed to achieve a flavorful crust and evenly cooked interior. This method leverages the high heat retention properties of cast iron to facilitate rapid searing and consistent temperature control. The result is a steak exhibiting a desirable Maillard reaction on its surface and a tender, juicy center.

Utilizing a cast iron skillet offers several advantages for steak preparation. The even heat distribution minimizes hot spots, leading to more uniform cooking. Furthermore, the high heat capacity allows for effective searing even when a cold steak is introduced to the pan. The durability and longevity of cast iron cookware, coupled with its versatility, render it a valued tool in culinary practice, with documented use tracing back centuries in various cultures.

The following sections will detail the specific steps required for proper execution, including steak selection, seasoning protocols, skillet preparation, searing and cooking times, and resting guidelines. Understanding each stage is crucial for achieving optimal results and consistently producing a high-quality steak.

1. Steak Selection

The selection of a suitable ribeye steak directly influences the outcome of the cast iron skillet cooking method. The quality, thickness, and marbling of the chosen cut determine its ability to withstand high heat and retain moisture, impacting the final tenderness and flavor.

  • Marbling

    Intramuscular fat, known as marbling, is a critical factor. Higher degrees of marbling, indicated by fine streaks of fat distributed throughout the muscle, contribute to enhanced flavor and juiciness. During cooking, this fat renders, basting the steak from the inside and preventing dryness. Ribeyes graded as USDA Prime or Upper Choice typically exhibit superior marbling compared to lower grades.

  • Thickness

    Steak thickness directly affects cooking time and the ability to achieve a desirable sear without overcooking the interior. A thickness of at least 1.25 inches is generally recommended for cast iron cooking. Thinner steaks are prone to drying out before a proper crust can develop, whereas thicker steaks provide a greater window for error, allowing for better temperature control during the searing process.

  • Cut Quality and Source

    The origin and handling of the ribeye influence its ultimate quality. Dry-aged ribeyes, for example, undergo a process of controlled dehydration, concentrating flavor and tenderizing the muscle. Grass-fed beef, while often leaner, may exhibit a different flavor profile compared to grain-finished beef. The source and butchering practices, therefore, contribute significantly to the overall dining experience.

  • Bone-in vs. Boneless

    The presence of a bone in the ribeye (bone-in ribeye, also known as a cowboy ribeye) can impact cooking dynamics. The bone acts as an insulator, potentially leading to slower and more even cooking near the bone itself. Some proponents believe the bone imparts additional flavor during the cooking process, although scientific evidence for this is limited. Boneless ribeyes offer convenience and easier slicing post-cooking.

In summary, careful consideration of marbling, thickness, cut quality, and bone presence during steak selection is paramount for achieving a high-quality result when employing the cast iron skillet cooking method. These factors interact to influence tenderness, flavor, and overall palatability, ultimately determining the success of the dish.

2. Proper Seasoning

Proper seasoning is integral to the successful execution of ribeye preparation within a cast iron skillet. Salt, in particular, performs several functions beyond merely enhancing flavor. Applied in advance, salt draws moisture from the steak’s surface, which subsequently dissolves the salt and forms a brine. This brine is then reabsorbed into the muscle fibers, resulting in a more thoroughly seasoned steak and promoting improved moisture retention during cooking. The dried surface also contributes significantly to the formation of a desirable crust via the Maillard reaction.

The timing of seasoning application impacts the final outcome. Seasoning immediately before cooking results in surface seasoning only, failing to penetrate the meat effectively. Conversely, applying salt hours in advance, up to overnight, allows for optimal brine absorption and surface drying. Black pepper, while a common addition, can burn at high temperatures, potentially imparting a bitter flavor. Therefore, pepper is often added closer to the end of the cooking process or immediately after searing to mitigate this risk. Other seasonings, such as garlic powder, onion powder, or herbs, can be incorporated based on personal preference, but their application should consider their susceptibility to burning at high temperatures.

In summary, proper seasoning, specifically with salt applied well in advance of cooking, is a crucial step in achieving a well-crusted, flavorful, and evenly seasoned ribeye in a cast iron skillet. The principles of moisture control, brine absorption, and the timing of seasoning application are all interconnected and significantly impact the final product. The understanding and application of these principles are essential for consistently producing a high-quality steak.

3. Skillet Temperature

The thermal state of the cast iron skillet is a paramount factor in achieving a properly seared and cooked ribeye. Inadequate or excessive heat compromises the Maillard reaction, texture, and overall doneness of the steak. Precise temperature management is thus essential for optimal results.

  • Ideal Temperature Range

    The recommended skillet temperature for searing a ribeye typically falls between 400F and 450F (204C and 232C). This range allows for rapid surface browning and crust formation without overcooking the interior. Temperatures below this range result in insufficient searing, leading to a gray, steamed exterior. Temperatures exceeding this range can cause excessive charring and potential burning of the steak’s surface before the center reaches the desired doneness.

  • Preheating Duration

    Cast iron skillets require substantial preheating time to ensure even heat distribution and maintain a stable temperature during searing. A preheating duration of 8-10 minutes over medium-high heat is generally recommended. Insufficient preheating leads to temperature drops when the steak is added, hindering proper searing. Using an infrared thermometer to verify the skillet’s surface temperature is a reliable method to ensure it reaches the desired range.

  • Impact on Maillard Reaction

    The Maillard reaction, a chemical process between amino acids and reducing sugars, is responsible for the desirable browning and savory flavors associated with seared steak. This reaction occurs most effectively at high temperatures. A properly preheated cast iron skillet provides the necessary heat energy to drive the Maillard reaction, creating a rich, flavorful crust. Conversely, insufficient skillet temperature inhibits the Maillard reaction, resulting in a pale, less flavorful surface.

  • Maintaining Temperature During Searing

    Introducing a cold steak to a hot skillet inevitably causes a temperature drop. To mitigate this, avoid overcrowding the skillet and ensure the steak is relatively dry before searing. Maintaining consistent heat is crucial for continuous searing. In some instances, reducing the heat slightly after the initial sear can prevent burning while allowing the interior to reach the desired temperature. Adjustments may be necessary based on steak thickness and the efficiency of the stovetop.

The preceding factors highlight the critical role of skillet temperature in the process. Maintaining the appropriate temperature range, achieved through adequate preheating and monitored throughout the searing process, is fundamental for maximizing flavor development and achieving the desired level of doneness in the final product. Careful attention to these details significantly contributes to the successful preparation of a ribeye using the cast iron skillet method.

4. Searing Technique

The searing technique represents a crucial component in the endeavor to properly cook a ribeye within a cast iron skillet. It directly influences the development of a flavorful crust and significantly contributes to moisture retention within the steak. The application of high heat to the surface of the meat causes a series of chemical reactions, collectively known as the Maillard reaction, resulting in the formation of hundreds of flavor compounds. Simultaneously, the rapid coagulation of proteins at the surface creates a barrier that helps to minimize moisture loss during subsequent cooking stages. Failure to properly execute the searing technique compromises these benefits, leading to a less flavorful and potentially drier final product. As an example, a ribeye placed in a lukewarm skillet will not develop the characteristic crust, instead, it will simmer in its own juices, resulting in a gray, unappetizing appearance and a significant reduction in moisture content.

Effective searing involves several critical elements: a properly preheated cast iron skillet, a dry steak surface, and the application of consistent pressure. The skillet must be sufficiently hot to initiate the Maillard reaction immediately upon contact with the steak. A dry surface promotes rapid browning by eliminating the energy expenditure required to evaporate surface moisture. Applying gentle but consistent pressure ensures even contact between the steak and the skillet’s surface, maximizing heat transfer and promoting uniform crust formation. For instance, using a spatula or steak weight to gently press the ribeye against the skillet can significantly improve the sear quality, particularly on uneven surfaces. The duration of the sear varies depending on the thickness of the steak and the desired level of doneness but typically ranges from 2-4 minutes per side.

In summary, mastering the searing technique is essential for achieving optimal results when cooking a ribeye in a cast iron skillet. The high heat, dry surface, and consistent pressure are the key elements that drive the Maillard reaction and promote moisture retention. While other factors, such as steak selection and seasoning, contribute to the overall quality of the dish, the searing technique forms the foundation upon which a flavorful and tender ribeye is built. Overlooking or underestimating the importance of this technique presents a significant challenge to achieving a truly exceptional steak.

5. Even Cooking

Achieving uniform internal temperature, or “Even Cooking,” represents a critical objective when employing the cast iron skillet method for ribeye preparation. Variance in temperature across the steak’s mass results in differing degrees of doneness, potentially leading to an unsatisfactory culinary experience. The properties of the skillet, the technique applied, and pre-existing conditions within the meat itself significantly influence the attainment of even cooking.

  • Cast Iron Heat Distribution

    Cast iron cookware is recognized for its ability to distribute heat relatively evenly. However, variations can occur depending on the thickness of the cast iron and the heat source. Hot spots may develop, particularly over gas flames, leading to localized overcooking. Preheating the skillet thoroughly on a calibrated burner or using an induction cooktop can mitigate these effects. Periodic rotation of the skillet during cooking also aids in ensuring consistent heat exposure across the steak’s surface.

  • Steak Thickness and Initial Temperature

    The thickness of the ribeye directly affects the time required to achieve a uniform internal temperature. Thicker steaks necessitate lower cooking temperatures or indirect heat methods to prevent excessive surface browning before the center reaches the desired doneness. Furthermore, the initial temperature of the steak plays a role. Starting with a steak that has been allowed to come to room temperature for a period (approximately 30-60 minutes) promotes more even cooking by reducing the temperature differential between the surface and the core.

  • Flipping Frequency and Technique

    Traditional methods advocate for infrequent flipping of the steak, typically once per side. However, contemporary techniques suggest more frequent flipping (every 1-2 minutes) to promote more even cooking and reduce the formation of a thick, overcooked band beneath the seared surface. Frequent flipping minimizes temperature gradients within the steak, resulting in a more consistent internal temperature profile. The technique must be gentle to avoid disrupting the sear.

  • Use of a Meat Thermometer

    Accurate assessment of internal temperature is essential for achieving even cooking. A reliable meat thermometer, inserted into the thickest part of the steak, provides objective data on the steak’s progress. Regular temperature monitoring allows for adjustments to the cooking process, such as reducing heat or moving the skillet off the direct heat source, to ensure the steak reaches the desired level of doneness without overcooking any particular area. Removing the steak a few degrees before the target temperature accounts for carry-over cooking during the resting phase.

In summation, even cooking in cast iron ribeye preparation is a multifaceted process that demands attention to the cookware, the meat itself, and the cooking technique employed. Optimizing these elements through careful preheating, temperature control, strategic flipping, and the judicious use of a meat thermometer elevates the likelihood of achieving a ribeye that is uniformly cooked and satisfies expectations for both texture and flavor. The interplay between these elements highlights the importance of a holistic approach to this culinary endeavor.

6. Internal Temperature

The accurate measurement and management of internal temperature constitute a critical determinant in successfully employing the cast iron skillet method for ribeye preparation. Internal temperature directly dictates the degree of doneness, influencing the steak’s texture, juiciness, and overall palatability. An undercooked ribeye presents an undesirable raw or excessively chewy texture, while an overcooked steak becomes dry and tough. The cast iron skillet, while effective for searing, requires careful monitoring of internal temperature to ensure the steak reaches the desired level of doneness throughout, rather than simply exhibiting a browned exterior.

Consider a scenario where a ribeye is seared in a cast iron skillet without temperature monitoring. The exterior may develop a visually appealing crust, leading to the assumption that the steak is properly cooked. However, upon slicing, the center may reveal an undercooked interior, rendering the steak unappetizing. Conversely, prolonged cooking in the skillet without temperature checks can result in an overcooked steak, despite the initial sear being executed correctly. The integration of a meat thermometer into the cooking process allows for precise control over the steak’s doneness, ensuring that it aligns with individual preferences, whether rare, medium-rare, medium, or well-done. The USDA provides recommended internal temperature guidelines for different levels of doneness, which serve as benchmarks for achieving consistent results.

In summary, internal temperature measurement serves as an indispensable tool for optimizing ribeye preparation within a cast iron skillet. It bridges the gap between visual assessment and actual doneness, enabling cooks to achieve consistent and predictable results. While techniques like searing and basting contribute to flavor and texture, the ultimate success hinges on reaching the appropriate internal temperature. Consistent monitoring with a meat thermometer, combined with an understanding of carry-over cooking, ensures a ribeye that is both flavorful and cooked to the desired level of doneness, highlighting the practical significance of this element.

7. Resting Period

The resting period, following the searing and cooking stages, constitutes an essential phase in the preparation of ribeye using the cast iron skillet method. This interval allows for redistribution of moisture within the steak, impacting the ultimate tenderness and juiciness of the final product. Neglecting this step compromises the textural quality of the cooked ribeye, regardless of the precision applied during the cooking phase.

  • Moisture Redistribution

    During cooking, the high heat causes muscle fibers to contract, expelling moisture towards the center of the steak. The resting period provides an opportunity for these fibers to relax and reabsorb the expelled moisture. This reabsorption results in a more evenly hydrated steak, enhancing its perceived juiciness. If the steak is sliced immediately after cooking, a significant amount of this moisture is lost, resulting in a drier eating experience. Scientific studies employing diffusion models demonstrate this process of moisture equilibration within cooked meats during resting.

  • Temperature Equalization

    The resting period also facilitates temperature equalization throughout the steak. Even with careful temperature monitoring, gradients can exist between the outer layers and the center. As the steak rests, heat transfers from the warmer outer layers to the cooler center, resulting in a more uniform internal temperature. This temperature equalization contributes to a more consistent texture and doneness across the entire steak. Premature slicing disrupts this process, potentially exposing an undercooked center.

  • Duration and Environment

    The optimal resting period for a ribeye cooked in a cast iron skillet typically ranges from 5 to 10 minutes, depending on the thickness of the steak. The steak should be rested loosely covered, such as with foil, to retain some heat without steaming the surface. Resting uncovered allows excessive heat loss, while tightly wrapping the steak can trap moisture and soften the seared crust. The ambient temperature of the resting environment also affects the rate of heat loss; a cooler environment necessitates a slightly shorter resting period.

  • Impact on Slicing

    The resting period significantly impacts the ease and quality of slicing. Allowing the muscle fibers to relax prior to cutting reduces resistance, resulting in cleaner, more uniform slices. Slicing a steak immediately after cooking often results in ragged edges and uneven portions, as the contracted muscle fibers resist the knife. Furthermore, the moisture redistribution facilitated by resting reduces moisture loss during slicing, preserving the steak’s juiciness until consumption.

In conclusion, the resting period is not merely a passive step but an active process that significantly influences the final quality of a ribeye cooked in a cast iron skillet. The moisture redistribution, temperature equalization, and improved slicing characteristics resulting from proper resting contribute to a more tender, juicy, and visually appealing steak. These benefits underscore the importance of incorporating this stage into the cooking process to maximize the potential of the ribeye cut and the cast iron skillet method.

8. Butter Basting

Butter basting represents a technique frequently integrated into the cast iron skillet method for ribeye preparation, exerting a notable influence on both flavor and moisture retention. The practice involves spooning melted butter, often infused with aromatics such as herbs and garlic, over the steak during the latter stages of cooking. This process serves to baste the steak with a rich, flavorful liquid, contributing to a more succulent and savory final product. The high fat content of butter also aids in heat transfer, promoting more even cooking and surface browning. For instance, a ribeye seared to a desirable crust can benefit from butter basting to further enrich its flavor profile and maintain its moisture content as it reaches the desired internal temperature.

The application of butter basting addresses specific challenges inherent in high-heat cooking methods. While searing in a cast iron skillet effectively creates a flavorful crust, prolonged exposure to high heat can lead to moisture loss from the steak’s surface. Butter basting mitigates this effect by continuously coating the steak with a protective layer of fat, preventing excessive evaporation and promoting a more tender interior. Furthermore, the incorporation of herbs and aromatics into the butter introduces additional layers of flavor complexity, complementing the natural richness of the ribeye. Chefs often employ this technique to elevate the steak beyond simple searing, transforming it into a more sophisticated culinary offering. A comparative example reveals that a ribeye cooked solely by searing, without butter basting, tends to exhibit a drier texture and a less nuanced flavor compared to its butter-basted counterpart.

In summary, butter basting serves as a valuable adjunct to the cast iron skillet method for ribeye cooking, addressing moisture retention concerns and enhancing flavor complexity. The technique’s effectiveness relies on the strategic application of melted butter, often infused with aromatics, during the final stages of cooking. The practical significance of this understanding lies in the ability to consistently produce a ribeye that is both flavorful and succulent, elevating the overall dining experience. The integration of butter basting exemplifies how specific techniques can be employed to optimize the cast iron skillet method and achieve superior results.

9. Deglazing Pan

Following the preparation of a ribeye in a cast iron skillet, deglazing the pan represents a technique to reclaim flavorful residues. These residues, or fond, consist of caramelized meat juices and fats that adhere to the skillet’s surface during cooking. Deglazing involves introducing a liquid to the hot pan to dissolve these flavorful components, creating a sauce or base for a sauce.

  • Solvent Selection

    The choice of liquid solvent directly influences the flavor profile of the resulting sauce. Red wine is a common selection, imparting a rich, complex flavor that complements beef. Other suitable options include beef broth, which provides a savory base, or even balsamic vinegar, offering a tangy counterpoint. The selected liquid should be added to the pan immediately after removing the ribeye, while the pan remains hot, to effectively dissolve the fond. Introducing the liquid to a cooled pan diminishes its ability to lift the caramelized residues.

  • Aromatic Infusion

    Deglazing provides an opportunity to infuse the sauce with additional aromatics. Shallots, garlic, or herbs can be added to the pan prior to introducing the liquid. These aromatics saut in the residual fat, releasing their flavors and enhancing the complexity of the sauce. The timing of aromatic addition is critical; adding them too early can result in burning, while adding them too late may not allow sufficient flavor extraction. Sauting the aromatics for a brief period, typically one to two minutes, before adding the liquid optimizes flavor infusion.

  • Reduction and Emulsification

    Following the introduction of the liquid, the sauce is typically reduced to concentrate its flavor and thicken its consistency. Simmering the sauce over medium heat allows the liquid to evaporate, resulting in a more intense flavor profile. Emulsification, the process of combining fat and liquid into a stable mixture, can be achieved by whisking in a small amount of butter towards the end of the reduction. This creates a richer, smoother sauce. Proper emulsification requires gradual incorporation of the butter and consistent whisking to prevent separation.

  • Straining and Seasoning

    After reduction and emulsification, the sauce can be strained to remove any solids, such as caramelized bits or herb stems, resulting in a smoother texture. A fine-mesh sieve is typically used for this purpose. The strained sauce should then be seasoned to taste with salt and pepper. Additional seasonings, such as Worcestershire sauce or Dijon mustard, can be added to further enhance the flavor profile. Careful seasoning is essential to balance the flavors and create a harmonious sauce that complements the ribeye.

Deglazing, therefore, represents an efficient method to transform otherwise discarded pan residues into a flavorful sauce that enhances the overall dining experience. The careful selection of solvent, strategic infusion of aromatics, controlled reduction, and judicious seasoning are all critical elements in maximizing the potential of this technique. The resulting sauce serves as a complement to the ribeye, enriching its flavor and adding a professional touch to the preparation.

Frequently Asked Questions

This section addresses commonly encountered inquiries regarding the process of cooking a ribeye steak within a cast iron skillet, offering clarifications and best practice guidelines.

Question 1: What constitutes the optimal fat content for a ribeye intended for cast iron skillet preparation?

The presence of intramuscular fat, commonly referred to as marbling, is a key determinant of flavor and moisture retention. A ribeye exhibiting abundant marbling, graded as USDA Prime or Upper Choice, is generally considered optimal. This fat renders during cooking, basting the steak from within and preventing dryness.

Question 2: How long should a cast iron skillet be preheated prior to searing a ribeye?

A preheating duration of 8 to 10 minutes over medium-high heat is generally recommended. The objective is to ensure the skillet reaches a consistent temperature between 400F and 450F (204C to 232C). Insufficient preheating impairs searing and crust formation.

Question 3: What is the recommended technique for seasoning a ribeye prior to cooking in a cast iron skillet?

Generous application of kosher salt is recommended, ideally several hours in advance or even overnight. This allows the salt to penetrate the meat, enhancing flavor and promoting moisture retention. Black pepper and other seasonings may be added closer to cooking to prevent burning.

Question 4: Is it necessary to use oil in the cast iron skillet when searing a ribeye?

A high-smoke-point oil, such as canola or avocado oil, is recommended. A thin, even coating of oil in the skillet facilitates heat transfer and prevents the steak from sticking. The quantity of oil should be sufficient to lightly coat the surface, avoiding excessive pooling.

Question 5: What is the ideal internal temperature for a medium-rare ribeye?

The target internal temperature for a medium-rare ribeye is 130F to 135F (54C to 57C). A reliable meat thermometer inserted into the thickest part of the steak is essential for accurate temperature assessment. Remove the steak from the skillet a few degrees before reaching the target temperature to account for carry-over cooking during resting.

Question 6: How long should a ribeye rest after cooking in a cast iron skillet?

A resting period of 5 to 10 minutes is recommended. This allows the muscle fibers to relax and redistribute moisture, resulting in a more tender and juicy steak. The steak should be rested loosely covered with foil to retain heat without steaming the surface.

Proper execution of ribeye preparation in a cast iron skillet requires attention to details encompassing steak selection, seasoning protocols, skillet temperature management, searing technique, internal temperature monitoring, and adequate resting. These elements collectively contribute to a high-quality culinary outcome.

The following section provides guidance on troubleshooting common issues encountered during the cooking process, offering solutions to address potential challenges and optimize results.

Tips for Ribeye Excellence in Cast Iron

The following tips offer refinements for consistent and superior results when employing the cast iron skillet method for ribeye steak preparation. These guidelines focus on optimizing flavor, texture, and overall execution.

Tip 1: Reverse Sear for Enhanced Doneness Control. Initiate cooking at a low oven temperature (around 250F or 121C) until the steak reaches approximately 10-15F (5-8C) below the desired final internal temperature. Then, transfer to the preheated cast iron skillet for searing. This technique promotes even cooking from edge to edge.

Tip 2: Clarify Butter for a Higher Smoke Point. Regular butter contains milk solids that burn easily at high temperatures. Clarifying butter by removing these solids raises its smoke point, making it more suitable for searing and basting without producing acrid flavors.

Tip 3: Optimize Skillet Size for Efficient Searing. Select a cast iron skillet that closely matches the size of the ribeye. Excessively large skillets require more energy to preheat and may result in uneven searing. Conversely, a skillet that is too small can overcrowd the steak and lower the pan temperature.

Tip 4: Employ a Steak Weight for Uniform Crust Formation. Using a heavy steak weight or press on the ribeye during searing ensures consistent contact with the hot skillet surface, promoting uniform crust development. This is particularly useful for steaks with uneven surfaces.

Tip 5: Introduce Aromatics Strategically During Basting. Add herbs such as thyme or rosemary and aromatics like garlic cloves to the skillet during the basting process. Introducing these elements late in the cooking cycle allows their flavors to infuse the butter without burning.

Tip 6: Dry-Brine for Enhanced Flavor and Tenderness. Apply kosher salt to the ribeye 12-24 hours prior to cooking. This “dry-brining” process allows the salt to penetrate deep into the muscle fibers, enhancing both flavor and moisture retention. Pat the steak dry before searing to promote optimal crust formation.

Tip 7: Consider Sous Vide Pre-Cooking. For unparalleled doneness control, pre-cook the ribeye using the sous vide method. Submerge the steak in a temperature-controlled water bath until it reaches the desired internal temperature. Then, sear in the cast iron skillet for a quick, intense crust.

These tips, when integrated into the cast iron ribeye cooking process, offer heightened control over flavor development, texture optimization, and overall execution, resulting in a superior culinary outcome. Understanding and applying these techniques refines the skill set required for consistent high-quality results.

The subsequent section presents concluding remarks, summarizing the key takeaways and reinforcing the advantages of mastering the art of ribeye preparation in a cast iron skillet.

Conclusion

The preceding sections have detailed the process of how to cook ribeye in a cast iron skillet, underscoring critical factors from steak selection and seasoning to skillet temperature, searing technique, internal temperature management, resting period optimization, basting strategies, and pan deglazing procedures. Mastery of these elements is essential for consistently producing a high-quality steak.

Achieving proficiency in cooking ribeye using a cast iron skillet provides a versatile and reliable method for producing exceptional results. Continued practice and attention to detail will further refine technique, enabling consistent delivery of a superior culinary experience. The principles outlined extend beyond this specific application, offering transferable knowledge applicable to other steak preparations and cooking methodologies.