Flat Iron Steak is marinated and grilled for a tender and flavorful main dish protein, perfect for weeknight dinners or a summer backyard party. This is a great cut of beef that’s juicy, flavorful, and well marbled.

As a family that eats beef every single day, we’ve become very familiar with all the different cuts.

It’s easy to fall in love with pieces like new york strip or filet mignon, but the cost is often too high for anything but a special occasion.

Flat iron steak, on the other hand, is quite affordable!

At my local grocery store, NY strips run about $18/lb and filet at $32/lb, but flat iron steaks are only $10/lb. Even cuts like flank steak and skirt steak, which are often compared to flat iron, are a whopping $16/lb.

The flat iron cut has a delicious flavor that you can certainly enjoy without any additional seasonings except some salt and pepper, but I’ve included a simple marinade that really enhances the flavor and makes for an extra juicy flat iron steak recipe.

I’m going to show you how I cook it to a perfect medium rare to medium doneness, with a well browned exterior and a tender interior.

High temperature and a well preheated grill are key for ensuring a juicy steak and best results.

Ingredients You’ll Need

For the steak marinade, we will use olive oil, red wine vinegar, tamari (or soy sauce), fresh garlic cloves, fresh rosemary, kosher salt, and black pepper.

Though I pair this with flat iron steak, you may use this marinade for other steak cuts of beef as well. But I love how flavorful and marbled this steak is, which you can see:

It’s one of my favorite cuts of beef, and quite tender for the most part, but know that there is some gristle running through it.

Also, note that some grocery stores will sell top blade steak instead of flat iron, which is the same muscle coming from the shoulder area of the cow, but cut differently. It will have a similar flavor, but has a strip of gristle running down the middle.

Step by Step Overview

In a resealable plastic bag, combine the extra virgin olive oil, red wine vinegar, tamari, minced rosemary, pressed or minced garlic, and freshly ground black pepper:

As for the salt, in my opinion it is not needed unless you are using a low sodium tamari or soy sauce. If you are using “regular” soy sauce, do not add any extra salt.

Mix the marinade ingredients up by giving the bag a swirl, then add your steaks to the plastic bag.

Zip the bag almost all the way closed, leaving a small space for pushing out any excess air.

How long to marinade

I think 4 hours is the perfect amount of time, though you can also get away with as little as 1 hour, or up to 1 day ahead of time.

If you are marinating for only 1 hour and are then grilling and eating right away, you may leave the bag at room temperature. Otherwise, marinate in the refrigerator.

After marinating, it’s time to grill!

Unlike thicker steaks like Grilled Ribeye, it is not necessary to take the beef out of the fridge ahead of time to warm up, and I find that it’s actually better that the beef is on the colder side so you can thoroughly brown the outside without overcooking the interior.

Preheat a gas grill to high for at least 10 minutes, using all burners.

Then place the steaks onto the hot grill grates:

Close the lid, then cook for 90 seconds.

If the grill was thoroughly preheated, you should be able to lift up the beef after this minute and a half, and see some good grill marks underneath:

Now turn all of the pieces 90 degrees the other way, so you get grill marks in the opposite direction. I also move them slightly off center, so they have more searing on the uncovered section of grill grates:

Close the lid for another 90 seconds, then flip the steaks over and do another 90 second cook with the lid closed again:

Do one final turn 90 degrees to get grill marks going the other way, then check the internal temperature using a meat thermometer.

Temperatures for Doneness:

I love to enjoy flat iron steak at medium rare, but here are guidelines for other levels of doneness:

  • Rare – 125°, very red inside, cool interior
  • Medium rare – 135°, red inside and warm
  • Medium – 145°, pink inside and warm
  • Medium well – 150°, slightly pink inside and warm
  • Well – 160°, no pink inside

Make sure to insert your instant-read thermometer through the side of the steak, into the center.

Remember that carryover cooking will add another 5 to 10 degrees of temperature after you pull the beef off the grill.

So pulling the steak off at 126 degrees F is perfect for hitting a final temperature closer to 135F.

For best results, let the steak rest on a wire rack, plate, or tray for at least 5 minutes, before slicing on a cutting board. 

If you cut into the beef right away, all the tasty juices will run out onto your plate. Resting gives the juices time to redistribute and stay in the meat when you slice it.

After you’ve made this recipe, give my Grilled Flank Steak marinade a try as well. That one is made with balsamic vinegar and dijon mustard instead.

Suggested Side Dishes

Steak tends to go well with most sides, and this marinade is basic enough that it won’t clash with most side dish pairings. Here are some of my favorite choices:

Salads – Enjoy with this Tomato Burrata Salad or White Bean Salad.

Roasted vegetables – Try Roasted Brussels Sprouts, Roasted Cauliflower, or Roasted Fennel.

PotatoesCrispy Smashed Potatoes, Red Potato Salad, and Homemade French Fries are all delicious options.

Recipe Tips and FAQ

Do you have to use fresh herbs?

You may use 2 teaspoons of dried herbs instead, though I really think freshness makes a huge difference here.

Can you use other kinds of vinegar?

Red wine vinegar goes beautifully with beef, but you can also use a quality white wine vinegar, apple cider vinegar, or a light balsamic vinegar. I do not recommend using lemon juice.

Can you use a charcoal grill?

Absolutely. Try to focus on creating at least a solid medium-high heat so you get a good caramelized exterior on the beef.

What if you don’t have a grill?

You can pan sear this as well in a hot skillet, for about the same amount of time as the grill (check for doneness using an instant read thermometer). I recommend using a cast iron pan, which preheats well. Make sure to pat the steaks dry with paper towel before searing.

Did you enjoy the recipe? Please leave a 5-star rating in the recipe card below and/or a review in the comments section further down the page. Or, follow me on Facebook, Instagram or Pinterest!

Sliced Marinated Flat Iron Steak on Wooden Board

Marinated and Grilled Flat Iron Steak

Flat iron steaks are marinated with red wine vinegar and fresh rosemary for a tender and delicious flavor, then grilled until well browned on the outside, but tender in the middle.
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Ingredients

  • 3 flat iron steaks (1.5lbs total)*
  • cup olive oil
  • ¼ cup soy sauce or Tamari for gluten-free**
  • 2 tbsp red wine vinegar
  • 4 cloves garlic pressed or minced
  • 2 tbsp chopped fresh rosemary
  • ½ tsp black pepper

Instructions 

  • Combine everything except the flat iron steak (the olive oil, soy sauce, red wine vinegar, garlic, rosemary, and black pepper) in a gallon-sized ziptop plastic bag. Shake or swish the bag to combine.
  • Place the flat iron steak in the bag of marinade and squeeze out as much air as possible before closing the bag tightly. Squeezing out the air ensures that the beef is sufficiently coated in the marinade.
  • Marinate the meat ideally for 4 hours*** and up to 1 day ahead.
  • Preheat a gas grill on high for at least 10 minutes, heating all burners.
  • Remove the meat from the marinade, then place in the center of the grill. Close the lid, and cook for 90 seconds.
  • Check that there are grill marks underneath, then pivot the meat 90 degrees (I do this to an untouched part of the grill grates so I get the best possible sear on the beef), and again close the lid and cook for 90 more seconds.
  • Flip the steaks over. Close the lid, and cook for 90 seconds.
  • Pivot the meat 90 degrees to get grill marks going the other way again, close the lid, and cook for another 90 seconds.
  • Because this cut of beef is so thin, there's a good chance it's already done. Check internal temperature with a thermometer. I aim for between 125F and 130F, but you may cook to your desired level of doneness, repeating these 90 second intervals with the lid closed. Just remember that the meat will rise another 5 degrees or so while resting because of carryover cooking.
  • Remove the steaks to a wire rack or tray and let rest for at least 5 minutes before slicing and serving. Enjoy!

Notes

*You can marinate up to 4lbs of steaks with this marinade. However, if doing 4lbs of beef, add 2 tsp of additional salt. 
**If you are using regular soy sauce or tamari, there is no need to add extra salt. If you use low-sodium versions of these products, you may want to add an extra 1/2 teaspoon salt to the marinade. 
***4 hours is the ideal minimum for marinating time, but you can get away with as little as 1 hour. 
Storing leftovers: Keep in an airtight container in the fridge for up to 5 days.
Freezing: Store in an airtight container for up to 2 months.
Reheating: Place in a 250F oven for about 10 minutes, until the beef feels warm to the touch. You may also try the microwave, but use 50% power and check the beef frequently, as it will very quickly overcook and lose its pink and tender interior.

Nutrition

Calories: 518kcal, Carbohydrates: 2g, Protein: 49g, Fat: 34g, Saturated Fat: 11g, Polyunsaturated Fat: 2g, Monounsaturated Fat: 16g, Trans Fat: 1g, Cholesterol: 165mg, Sodium: 619mg, Potassium: 820mg, Fiber: 0.4g, Sugar: 0.2g, Vitamin A: 41IU, Vitamin C: 2mg, Calcium: 30mg, Iron: 6mg

Nutrition is estimated using a food database and is only intended to be used as a guideline for informational purposes.