Mom's Best Recipes
Recipe

Cast Iron Flat Iron Steak With Chimichurri

Crisp-seared flat iron steak, basted with garlic butter, then finished with a bright chimichurri for maximum flavor with minimal drama.

Author By Matt Campbell
4.8
A sliced flat iron steak fanned on a cutting board with bright green chimichurri spooned over the top, a cast iron skillet and warm kitchen lighting in the background
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Flat iron steak is one of my favorite "how is this not more famous?" cuts. It is beefy, tender when you slice it right, and it cooks fast enough to feel like a weeknight win. The vibe here is simple: get a hard sear, baste with butter for those cozy edges, then wake the whole thing up with a bright chimichurri that tastes like you tried harder than you did.

This recipe is written for a cast iron skillet because that heat is your best friend. No grill required, no fancy marinades that need a full day, and no sadness when you cut into it. Just steak that makes you pause mid-bite and go, “Okay, wow.”

Why It Works

  • Fast but special: flat iron cooks quickly and still feels like a steakhouse moment.
  • Great texture: ripping-hot pan equals crisp edges and a juicy center.
  • Big flavor without chaos: a quick marinade-rub seasons the surface, and the chimichurri brings brightness and balance.
  • Flexible doneness: you can nail medium-rare or push it to medium and it still eats tender.

Raw flat iron steak, parsley, cilantro, garlic, red wine vinegar, olive oil, salt, pepper, and red pepper flakes arranged on a light kitchen counter

Pairs Well With

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Storage Tips

Refrigerate: Store sliced or whole steak in an airtight container for up to 4 days. Store chimichurri separately for best color and punch.

Chimichurri make-ahead: It keeps well for 2 to 3 days in the fridge. The flavors mellow a bit as it sits, so taste and wake it up with a pinch of salt or a splash of vinegar right before serving.

Freeze: Freeze cooked steak (preferably unsliced) for up to 2 months. Wrap tightly, then place in a freezer bag. Chimichurri can be frozen too, but it will darken. Still delicious.

Reheat without turning it to jerky: Warm steak slices in a skillet with a small splash of broth or water over medium-low just until heated through. Or microwave at 50% power in short bursts. Add chimichurri after reheating.

Leftover ideas: Steak tacos, steak and eggs, chopped steak over a big salad, or a toasted steak sandwich with provolone and extra chimichurri.

Common Questions

What is flat iron steak, and is it tender?

Flat iron comes from the shoulder (the chuck), specifically the top blade. It is surprisingly tender because the tough connective tissue is removed in the butchering process, and it usually has nice marbling too. Cook it hot and fast and slice against the grain.

Do I need to marinate flat iron steak?

Not strictly. This is more of a quick marinade-rub situation: it seasons the surface really well and lets the salt work its way in a bit. If you are short on time, even 15 minutes at room temperature helps.

How do I know when the steak is done?

The easiest way is a thermometer. Time varies a lot by thickness, so use the clock as a guide and the thermometer as the boss. Pull it a little early because carryover heat finishes the job.

  • Rare: pull at 120°F, rest to about 125°F
  • Medium-rare: pull at 125°F, rest to about 130°F
  • Medium: pull at 135°F, rest to about 140°F
  • Medium-well: pull at 145°F, rest to about 150 to 155°F

Note: Doneness labels vary. USDA guidance for whole cuts is 145°F with a 3-minute rest.

Can I cook this without cast iron?

Yes. Any heavy-bottom stainless skillet works. Nonstick is not ideal for the sear you want.

Why did my steak turn out chewy?

Most of the time it is one of three things: the pan was not hot enough, the steak was overcooked, or it was sliced with the grain. Let it rest, then slice thinly across the long lines you see in the meat. Flat iron can have grain that shifts, so look at the fibers as you go and rotate the steak if you need to keep slicing perpendicular.

A hand slicing rested flat iron steak into thin strips across the grain on a wooden cutting board, with a chef's knife and natural kitchen light

I used to think steak night had to be a whole production. Then I met flat iron steak, and it changed my weeknight brain chemistry. It is the cut I grab when I want something that feels restaurant-y without trashing my kitchen. The first time I paired it with chimichurri, I realized something important: steak does not need a complicated sauce, it needs a bright one. Something herby and sharp that makes the fat taste even better. Now I keep a bunch of parsley in the fridge like it is a personality trait.