Cast Iron Flank Steak, Perfectly Seared

Back in culinary school, outdoor grills were not part of our routine. Steak after steak went into a hot pan, seared stovetop, until we got it just right. Over time, that method became second nature to me. And years later, I still lean toward the reliable stovetop method when I want a steak done just right.

How To Cook Flank Steak In A Cast Iron Skillet

In my books, a flank steak is one of the easiest cuts of steak to cook. And cooking flank steak on the stove required only a few simple rules:

• Pat Dry: Use a paper towel to pat the flank steak dry. Very dry. Any moisture left on the surface will compromise that golden sear (Maillard reaction) that elevates any steak to greatness.
• Season: Seasoning for a cast iron flank steak can be as simple as salt, pepper and garlic powder, or something regional. I focus on Southwestern recipes, so you’ll find a blend of Southwestern spices in this recipe.
• Heat: Don’t be afraid of heat. Heat your cast iron skillet over medium high heat until you can almost feel it starting to smoke. I like to hold a fist just above the skillet surface to gauge the heat level.
• Oil: Add a high smoke point neutral oil. Canola oil works well here. Olive oil is not a good choice. It’s unrefined and contains compounds that smoke at a lower temperature.
• Timing: Depending on the thickness of your flank steak, sear for only 3 – 6 minutes per side. And don’t mess with it. Turn it once.
• Internal Temperature: Use a good quality digital meat thermometer. Pull the steak from the pan when internal temperature reaches 125 degrees for medium rare.
• Tent: Place on a cutting board and tent with foil for 10 minutes. The internal temperature will rise to 130 – 135 degrees during this time.
• Slice: Very important to slice flank steak against the grain. Slice it thin and serve.

Cook time: 8 to 12 minutes, best doneness: medium rare, 125 to 130°F, total time: About 20 minutes including rest. That's it. Honestly, it’s that simple.

Why Cast Iron Is The Best Way To Cook A Flank Steak

Simply stated, flank steak needs high aggressive heat and a cast iron skillet is a master at holding heat. When a steak hits a cast iron skillet, the skillet’s ability to retain heat, doesn’t cool the pan down. Pan fried flank steak sizzles instantly and that sizzle equals flavor.

In Culinary School we talked about Maillard reaction like it was sacred, and it is. A slice of toast from a toaster is a perfect example of how Maillard reaction turns a simple piece of bread into a gourmet treat. Brown equals flavor, you don’t want a steak to be gray in color, you want a seared golden brown crust.

A Cast Iron Skillet is a master at returning:

• Serious crust.
• Edge to edge sear.
• It doesn’t let you down under high heat.
• Those browned bits on the bottom of the pan are magical if you’re making a quick pan sauce, or cooking charred onions for a topping.

1. Step 1: If Using: Make my flank steak Southwest seasoning paste: In a small bowl, combine the olive oil with the minced garlic, red chile powder, salt and cumin. Use a small whisk to combine. Set aside.

2. Step 2: Prep The Flank Steak: Remove the flank steak from the refrigerator and let it sit out for about 30 minutes. Adding a cold steak to a hot skillet causes the meat to tighten up. I’ve tried cooking it cold and at a warmer temperature. A warmer steak always wins out. Use a paper towel to pat the steak dry. Use your hands and rub the Southwest seasoning over both sides of the steak.

3. Step 3: Preheat The Cast Iron Properly: Turn you burner to medium high and add the cast iron skillet. Let the skillet heat for about 5 minutes before adding the steak. You can even wait until you see a faint wisp of smoke. Then you know for sure the skillet is nice and hot.
4. Step 4: Sear without moving it: Add the seasoned flank steak to the hot skillet, laying it down away from you. Let it sear about 5 minutes without moving it. Turn the steak and cook the 2nd side for 5 more minutes
5. Step 5: Check The Temperature: Use a digital read thermometer inserted into the thickest part of the steak. The temperature should read 125 degrees.

Tip: If you’re not using my oil based rub, you’ll need to add a couple tablespoons of oil to the pan before adding the steak.

6. Step 6: Rest The Flank Steak: Remove the steak to a cutting board and tent for about 10 minutes. This will allow the internal temperature to rise a few degrees, and will allow the juices to redistribute so they don’t run all over the cutting board when you slice.
7. How To Slice Flank Steak: It’s so important to slice flank steak against the grain. And luckily a flank steak grain is easy to see. Look for the fiber muscles, they run in clear lines. Slice it thin and this will keep the flank steak nice and tender.

Tip: How To Cut A Flank Steak So It Will Fit In Your Skillet. Flank steak too big for your skillet? You can cut it into 2 – 3 smaller uniform pieces. Use a sharp knife and cut the steak against the grain. When cooking flank steak in smaller pieces, be sure not to crowd the skillet. You need air to circulate around each piece for that golden crust.

Flank Steak Internal Temperature Guide

If I'm cooking for myself? I choose medium or medium rare, every time.

How Long To Cook Flank Steak In A Cast Iron

It truly depends on thickness.

• 1″ thick, around 3 – 4 minutes per side.
• 1 ½″ thick, closer to 5 minutes per side.
• Important: Don’t cook by clock alone. Look for a deep brown crust, firm but slightly springy feel and internal temperature starting in the 120’s.

Thermometer beats guess work, everytime.

Common Mistakes When Cooking Flank Steak On The Stove

I've made all of these. Yes, even after culinary school.

• Cooking past medium. Please know that cooking flank steak too long will compromise tenderness.
• Slicing with the grain. What a disaster. It’s hardly chewable.
• Skipping the rest time. All of the juices run out onto the cutting board.
• Starting with a lukewarm pan. That initial sizzle means that any remaining moisture is quickly cooking out of the surface of the meat. A sizzling skillet will trigger that beginning of that golden crust.

Variations

• While the steak is resting, quickly add rings of sweet onion to the skillet. Cook stirring until well charred. Spoon over steak and serve.
• Add a spoon of Steak Butter while it rests.
• Add a few slices to a warmed tortilla along with a slice of avocado for tacos.
• Layer onto a steak salad.
• Spoon chimichurri over the top.

Topping Ideas For Flank Steak

Personal Tip: Flank Steak With Charred Onions: (our favorite) Once you’ve tented the flank steak, throw a sweet onion that been cut in ⅛ inch slices into the still hot skillet. Cook the onions, stirring until charred and tender. This will take about 5 minutes. Slice the steak and top with the onions. Simply delicious.

The Southwest seasoning I’ve suggested will most certainly pair well with any of these Southwestern salsas and sauces for additional flank steak topping ideas:

• Sweet Spicy Jalapeno Pineapple Salsa
• Chipotle Peach Salsa
• Salsa Macha (Mexican Chile Oil)
• For pure and bold Southwest flavor, drizzle with New Mexico Red Chile Sauce, or Hatch Green Chile Sauce.
• And we love this steak topped with Red Onion Chutney.

Storage and Reheating

• Refrigerator: Store, well sealed in the refrigerator for up to 4 days.
• Freezer: Wrap well to freeze for up to 3 months. Remember to use a Sharpie and label with content and date.
• Reheating: Let the steak thaw in the refrigerator overnight. Gently reheat in a skillet over very low heat, just until warm enough to eat. Microwave? No for any meat. It dulls the texture.

Honestly, leftovers the next day in a tortilla! Delicious.