How to Cook Flat Iron Steak in Cast Iron Skillet to ‘Mmmmm…’!

Last Updated on by SteakEat

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This guide explains how to cook flat iron steak in cast iron skillet to medium-rare level of doneness.

You know the way you go ‘mmmmmm…’, when eating a darn good steak? 🙂

This is what this article will help you get – a juicy, tender and awesomely delicious flat iron steak. 😉


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We’ll be using a heavy cast iron skillet, which is like a guarantee that we get a good sear on the flat iron.


Are you prepared to take your flat iron steak to the next level? Let’s get started!


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Part 1: The Preparation of Your Flat Iron and the Cooking Process

Remember that we have yet to discuss choosing the perfect flat iron steak and tools that are needed for the searing process. I am assuming that your steak and your utensils are already in hand. If you are not prepared for the searing process, I recommend that you read Part 2 first.

Before we start, make sure you possess the necessary ingredients:

  • 8oz/230g flat iron steak (preferably matured 21 days and cut from organic grass-fed cattle)
  • 1 tbsp coconut oil or ghee
  • Kosher salt
  • Whole black peppercorns to grind

Make sure you have the proper equipment for this process including:

  • A cast iron skillet to sear in (preferably one that features grill marks)
  • Ideally 2 meat probes – one instant-read and one oven-safe probe
  • Tongs
  • Paper towels

And now – let’s SteakEat!

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Part 2: Searing Flat Iron in Cast Iron Skillet – 5 Easy Steps

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Step 1: Room Temperature

If you want your flat iron to be the best, it needs to be seared at room temperature.

An 8 ounce portion of flat iron should be removed from the refrigerator 40 minutes before cooking.

Larger pieces may take as much as two hours to arrive at room temperature.


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Step 2: Heating Your Cast Iron

One of the greatest advantages of cast iron is that once it arrives at temperature it can retain that heat through the entire cooking process.

The downside, however, is that cast iron skillets take ages to heat when compared to aluminum or steel skillets.

Another disadvantage is that they can cause your steak to stick and burn if they are not prepared properly.

To avoid ruining your dinner, season the skillet before adding the steak. Here is how:

  1. Place the skillet over heat until it reaches medium-high temperature (around 5 minutes at high heat). Add coconut oil or ghee and distribute it around the pan.
  2. Then remove the skillet from heat and set it aside to cool.
  3. Once the pan has cooled wipe it using paper towels to complete the seasoning process. It is now ready to be reheated for cooking.

You will want to wait for the skillet to heat on high for a minimum of 10 minutes before adding your flat iron steak. This will achieve a temperature high enough to sear the steak.


Side Note:

If you notice your pan started giving out gentle smoke before the 10 mins ran out, wait for another 40 seconds – your skillet is now ready for searing.



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Step 3: Pat Dry and Season the Flat Iron Steak

Those 10 minutes your skillet is eating can be spent prepping the steak for cooking.

The first step is to pat your flat iron dry using a light tapping motion. This dries the surface, which helps with browning later on.

Once the surface is dried, use kosher salt as the only seasoning.

I personally add 2-3 pinches per side.

Do not add pepper to your flat iron before cooking.

It has a high likelihood of burning during the cooking process and will result in a charred taste.

It is best to add pepper after the searing process.



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Step 4: Searing the Steak


Once the skillet is hot enough, place the steak in it.

If you have achieved the right amount of heat, you will hear a gentle sizzling sound.

Now you must determine how long to cook the flat iron.

A good rule of thumb when searing steak is to cook it 2,5 minutes on each side to achieve medium-rare doneness.

Cook the first side of the steak for 1.5 minutes over the grill marks.

After this time turn it 90 degrees so that the final design is a #-mark.

Then flip the flat iron using the tongs and complete this process on the opposite side.

Finish by cooking the flat iron 2 minutes per lateral side.

This step is the one that makes you recognize the why tongs are the preferred utensil for steak cooking.


Side Note:

Flat iron can become chewy and dry if overcooked.

That’s why I recommend not going beyond medium-rare doneness level (55C / 130F).

An instant read thermometer will be the best way to test for medium-rare doneness.

Insert the instant read thermometer into the center of your steak cut.

It should read 55C or 130F if you have achieved the appropriate medium-rare temperature.

Remember that this searing process works best for flat irons that are under 2.5cm, or 1 inch thick.



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Step 5: Rest Before Cutting

Unless you have a thicker cut, the entire process for searing should be completed in 10 minutes (3 min. per side + 2 min. per lateral side).

After it has reached the proper doneness, place the flat iron on a cutting board or plate.

This is when you grind your black pepper and add it to your steak.

Rest the steak on the board or plate for 3-4 minutes.

This stabilizes the juices of the steak so they do not run when the flat iron is cut into.

After the resting process is complete cut into the flat iron using a sharp knife.

You should cut across the grain, or muscle fibers, to ensure retention of its juices. This juicy, tender cut can then be served alone or with a side for a full meal.


steakeat-approvedFREE Bonus:

[ninja-popup ID=2908]Download this ‘How to Cook Flat Iron in Cast Iron Skillet’ Guide in PDF format.[/ninja-popup]

It is convenient, EASY-to-print and includes these awesome photos from above!


Find tips for choosing your steak and tools, tips to help the cooking process, and even recipes to enhance the flavor of your flat iron – continue to Page 3.


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Part 3: Selecting the Perfect Cut & the Tools that You Need

We have already discussed the preparation and searing of your flat iron in Part 1. We will soon look at recipes in Part 3.

For now – let’s choose a quality flat iron steak!

Greatness cannot be achieved with just any cut of flat iron.

A good guideline to follow when purchasing steak is that overall quality is directly related to the price.

There are several things to consider when purchasing steak.

Some factors that should influence your decision include:


Organic grass-fed. Conventional beef farmers tend to use antibiotics and growth hormones to raise their cattle to give larger amounts of meat. They also feed it grain feed, which is cheaper and more effective at fattening cows than grass feed. However, these things affect the meat flavor. Organic grass-fed cattle are raised without the use of antibiotics and growth hormones and are fed grass-like feed during their life. This results in a leaner, more flavorful cut of steak that is also healthier to eat.


Dry aging. When a cut of steak is chewy and lean, it’s trickier to cook it so it’s tender. You can remedy this by spending money on dry aged meat. Dry aging is a naturally occurring chemical process that encourages the breakdown of proteins in meat. This concentrates the flavor and makes your flat iron steak tenderer. The types associated with dry age include 28, 21, and 14-day maturity. It is more expensive than other steaks, but it makes up for it in flavor. In my opinion 21-day aged flat iron is the best choice from both, price and tenderness, points of view.


Weight and Thickness. The ideal serving size of steak is a portion of 7 ounces, or 200g, per person. This size results in a filling cut that you can enjoy without feeling bloated. For the searing method to work you should choose a cut no thicker than 2.5cm, or 1 inch. If you select a thicker cut of flat iron however, you will still be able to sear the steak using this guide and then finalize cooking in the oven to result in a juicy, tender, flavorful end steak.

Now that you have ensured you chose the right cut of flat iron, let’s get the equipment to sear it.


The Equipment You Need

The cut of flat iron steak you choose and the tools you use to sear it each make up 48% of your end result being a perfectly cooked steak.

What is the other 4% to this equation? Luck, of course.

To achieve perfection, this is the equipment you should use:


Cast Iron Skillet

Skillets made of cast iron have a thick, heavy build and incredible volumetric heating capabilities. They are great for searing your flat iron steak because once they get hot, they stay hot.

Cast irons also have handles that are resistant to heat, allowing them to be used in the oven. This is good if you chose a thicker steak, than is recommended for the searing process.

If the presentation of your steak is important, choose a cast iron with grill marks (#). These marks won’t do much for flavor but it will make your flat iron look as good as it tastes.



Tongs add ease the cooking process, especially for cooking with grill marks and while searing the lateral sides. They also work well for protection from burns.



Salt is the key component. When you add salt before high heat searing, it becomes part of the Maillard reaction, which is literally surface browning – salt helps to develop rich, exquisite flavor.

Kosher salt is ideal for steak cooking. It is less dense than table salt, meaning you can add more of it to encourage flavor without damaging the texture of your steak.



Freshly ground pepper is the best choice to add to your flat iron. Add it just before serving for a mouthwatering aroma.



For the high-temperature searing process you should choose heat-stable oil.

Personally, I recommend ghee or non-virgin coconut oil. Both have a high smoking point, work well at high temperatures, and add a great aroma to your dish.


Meat Thermometer

If you overcook your steak it will become dry. It will also lose its wonderful flavor and mouthwatering aroma.

So how can you ensure your steak is done, without overcooking?

You should keep two thermometers in your kitchen for times when you are cooking steak (or any meat/poultry really); an oven thermometer and an instant read thermometer.

Using a thermometer to check your steak will prevent overcooking.


Paper Towels

Paper towels are handy for cooking any type of meat. In this guide, we use paper towels to pat dry the surface of the flat iron before searing.

By the way, don’t try substituting paper towels with toilet paper – it doesn’t work.


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Part 4: Tips on Achieving the Perfect Flat Iron

I want to congratulate you once again on achieving a tender, juicy steak using the stovetop searing method in a cast iron skillet in Part 1.

Because you now possess basic knowledge and can buy quality flat iron steak using the guide in Part 2, we will discuss tips that can improve your future steak preparation processes.


Tip #1: Getting Your Steak to Room Temperature

In the flow of daily life you may forget to pull your flat iron from the refrigerator so it may arrive at room temperature before cooking. Fret not, there is an easy solution.

Set the steak on a plate. Heat it on the lowest setting in the microwave for 3-5 second intervals. Flip the steak at these intervals and continue cooking until the flat iron is warmed. Be careful not to cook it.


Tip # 2: Heat Your Skillet in the Oven

If you want to ensure even heating of your skillet, heat it in the oven instead of on stovetop. To do this, place the cast iron in an oven preheated to 200C or 400F. It will be properly heated in 15-20 minutes. Because the handle will be hot, be careful while removing the skillet from the oven.


Tip #3: Enhance the Flavor of Your Flat Iron

Add 1 knob organic grass-fed butter, 2-3 sprigs fresh rosemary, and 2 crushed garlic cloves to your skillet two minutes before you are done searing. Cook on one side for a minute and then flip your steak to allow the second side of your flat iron to absorb flavor. These ingredients enhance aroma and add to the overall flavor of your flat iron.


Tip #4: Preheat Your Plate

If you want to keep your flat iron warm after searing and before serving, preheat your plates in the oven. Preheat the oven to 90C, or 190F, and place the plates inside for 10 minutes.


Tip #5: Keep Your Flat Iron Warm and Juicy

There are many things that may prevent you from enjoying your steak as soon as it is done. To keep your steak warm while you clean up or act as host, place it in an oven preheated to 50C, or 120F. It will be kept at the ideal temperature for warmth, without cooking or becoming dry.


I hope you found this article useful and really enjoyed your cooking.

By no means this is a definitive guide – have you any comments, questions and tips, make sure to post them in the comments below. Thanks!


Ready To Enjoy That Juicy Tender Steak Every Single Time?

1. Get the Best Steak. Cooking steak to perfection is only 50% of success!
The other 50% come from great quality steak and I recommend you get those from here. Especially their grass-fed beef (they also have poultry, pork and loads of game!)