Use ingredients you probably already have in the kitchen to make this Flat Iron Steak Marinade. It turns an affordable piece of beef into something juicy, tender and super flavorful.

Orange liquid in a glass Pyrex measuring cup.

Unpopular opinion, but filet mignon is overrated. Yes, it’s very tender, but I don’t think it actually has that much flavor.

I much prefer a cheaper cut of meat, even if it needs a marinade. Cuts like flank steak and skirt steak can be SO tender and flavorful if prepared properly (and perfect wrapped in a tortilla with fajita toppings!).

And recently, I’ve discovered something called a flat iron steak.

Just like crock pot ribs are a much cheaper but still delicious alternative to a big double cut pork chop, flat iron steaks are a more affordable way to get your beef fix. And dare I say, a grilled flat iron steak is way tastier than filet mignon.

Today, I’m sharing my favorite marinade for a flat iron steak. It’s very likely you can make this with ingredients you already have in your kitchen! As you’ll see below, it’s VERY adaptable for what you have on hand.

A plastic wrapped flat iron steak with a butcher's sticker on it.

What is a flat iron steak?

A flat iron steak is a cut from the shoulder of a cow (just like country style ribs come from the pig’s shoulder). It is sometimes called a “top blade roast” or “patio steak.”

The entire top blade of the cow generally weighs between two and three pounds, and most butchers cut that into 4 flat iron steaks (about 8 to 12 ounces each).

Flat iron steaks generally have quite a bit of fat marbling running throughout them, which is what help makes them so tender and flavorful.

My favorite thing about flat iron steaks is how they are almost perfect rectangles, and are an even thickness throughout. That takes some of the guesswork out of grilling them!

Flat iron steak is perfect tucked into steak lettuce wraps or perched on top of steak tostadas.

Ingredients for a flat iron steak marinade on a light colored surface, including spices, brown sugar, chopped onions, halved oranges, oil, soy sauce and garlic paste.

Gather the ingredients for this flat iron steak marinade:

  • vegetable oil – or you can use olive oil here, but vegetable oil is much cheaper and I think it’s just fine for a marinade!
  • soy sauce – there’s no salt in this marinade for a flat iron steak, as all of the salt comes from the soy sauce. Don’t skip it! Soy sauce is also the secret ingredient in my homemade gravy.
  • onion – you just need a small hunk of onion, roughly chopped. I usually use white or yellow onion, just depending on what’s in my fridge. I’ve even used a couple of green onions when I have them.
  • garlic – you will need 1 clove of garlic for this flat iron steak marinade recipe.
  • orange juice – you can actually use ANY citrus juice here. I had oranges, but if you have lemons already on hand for citrus salad dressing, use those! Limes work too!
  • brown sugar – this adds sweetness to the marinade. If you have dark brown sugar, you can use that instead (it can also be used in my microwave caramel sauce).
  • chili powder – this adds a little mild heat to the marinade.
  • cumin – this adds a warm, earthy flavor to the steak.
A raw flat iron steak covered in marinade in a zip top bag.

A little secret about this flat iron steak marinade recipe:

My little secret is that I don’t measure anything when making this marinade (or my buttermilk chicken marinade, for that matter). Well, except the one time I measured so that I could include measurements in the recipe card below.

But every other time, I literally just eyeball every ingredient. Life is too short to have to clean a bunch of measuring cups and spoons for a marinade for a flat iron steak. Save those utensils for a baked good like Baileys brownies.

The exact ingredient amounts aren’t important here. As long as the general proportions are correct, the end result will be delicious.

So, go ahead, use a chunk of onion, a few squeezes of orange, a spoonful of brown sugar, and some dashes of spices. Honestly, you don’t need to measure anything for this flat iron steak marinade recipe.

How long to marinate flat iron steak:

Just like with root beer ribs, it’s best to marinate flat iron steak for at least four hours so that the flavors can start to soak into the meat, and the acidity can tenderize the steak.

You can also marinate overnight! However, try not to marinate longer than 24 hours if you can help it.

After TOO long, the acid in this flat iron steak marinade recipe will start to “cook” the beef (like how lime juice “cooks” the shrimp in shrimp ceviche), and the steak will be a little tough once you grill it.

A raw flat iron steak covered in marinade in a zip top bag.

What other steaks can you use this marinade for?

I also love this flat iron steak marinade recipe for flank steak, skirt steak and hanger steak. All of these cuts are relatively inexpensive, can be tenderized very well with a simple marinade, and are full of flavor.

More homemade marinades, sauces and dressings:

I almost always make my own marinades, sauces and salad dressings. I can control the ingredients that go into them, and make them to my taste preferences.

Orange liquid in a glass Pyrex measuring cup.

Flat Iron Steak Marinade

Yield: About 3/4 cup
Prep Time: 10 minutes
Total Time: 10 minutes

Use ingredients you probably already have in the kitchen to make this Flat Iron Steak Marinade. It turns an affordable piece of beef into something juicy, tender and super flavorful.

Ingredients

  • 1 clove garlic, roughly chopped
  • 1/4 small white onion, roughly chopped
  • 1/4 cup vegetable oil
  • 2 tablespoons light brown sugar
  • 2 tablespoons orange juice
  • 2 tablespoons soy sauce
  • 1/2 teaspoon chili powder
  • 1/4 teaspoon ground cumin

Instructions

  1. Place all ingredients in blender and blend until smooth. Makes a heaping 3/4 cup marinade, enough for about 1 pound of meat.

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Nutrition Information:
Yield: 4 Serving Size: 1
Amount Per Serving: Calories: 153Total Fat: 14gSaturated Fat: 1gTrans Fat: 0gUnsaturated Fat: 12gCholesterol: 0mgSodium: 450mgCarbohydrates: 7gFiber: 0gSugar: 6gProtein: 1g

This website provides estimated nutrition information as a courtesy only. You should calculate the nutritional information with the actual ingredients used in your recipe using your preferred nutrition calculator.

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