Flat Iron Steak Marinade
This Flat Iron Steak Marinade uses pantry staples to create juicy, flavorful steak without complicated ingredients. Learn exactly how long to marinate, how to avoid common mistakes, and why this combination works so well for flat iron steak.
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The Flat Iron Steak Marinade We Make All Summer Long
We may be in the minority here, but filet mignon is a little overrated. Yes, it’s very tender, but it doesn’t actually have that much flavor. We much prefer a cheaper cut of meat, even if it needs a marinade.
Flat iron steak is already one of the most flavorful cuts in the butcher case thanks to its rich marbling. That means we don’t need a complicated marinade loaded with dozens of ingredients.
Instead, we use a balanced combination of salty, sweet and acidic ingredients that enhance the beef rather than cover it up.
Why You Will Love This Marinated Flat Iron Steak
- This marinade balances salt, sweetness, acidity and aromatics so every bite tastes super savory without overwhelming the natural beef flavor.
- The ingredient list is built from pantry staples, making it easy to pull together on a weekday during grilling season.
- No measuring-cup marathon necessary. As long as the general proportions are right, this flat iron steak marinade turns out delicious, even when you’re just eyeballing the ingredients.
Flat Iron Marinade Ingredients
A full recipe card, including exact ingredient amounts, appears at the bottom of this post.
- flat iron steak – One of the most marbled and naturally tender value cuts available. You’ll need a 1-1/4 pound flat iron steak for this recipe.
- vegetable oil – helps coat the steak evenly and carries flavor across the surface of the meat. You can use olive oil here, but vegetable oil is much cheaper and we think it’s just fine for a marinade!
- soy sauce – adds both seasoning and umami to this great marinade. We’ve tested steak marinades with added salt, but soy sauce alone provides plenty of savory flavor.
- onion – you just need a small hunk of onion, roughly chopped. It creates a subtle sweet and savory backbone that makes the marinade taste more complex than its short ingredient list suggests. We usually use white or yellow onion, just depending on what’s in our fridge. We’ve even used a couple of green onions in a pinch.
- garlic – adds a pungent depth of flavor to the marinade.
- orange juice – you can actually use ANY citrus juice for this flat iron steak recipe. We had oranges, but if you have lemons already on hand, use those. Limes work too! The acid helps break down some of the tough connective tissue of the meat before cooking.
- brown sugar – balances the acidity and encourages the marinated steak to brown on the grill.
- chili powder – this adds a little mild heat to the marinade.
- cumin – this adds a warm, earthy flavor to the steak.
- flaky sea salt – a finishing touch that adds texture and highlights the beef’s natural flavor. We prefer Maldon brand.
How To Make The Best Flat Iron Steak Marinade
- BLEND. Place the garlic, onion, oil, brown sugar, orange juice, soy sauce, chili powder and cumin in a blender and blend until smooth.
- MARINATE. Place steak in a shallow baking dish or bowl, or large resealable bag. Pour marinade over steak and refrigerate at least 4 hours or up to overnight.
- ROOM TEMP. Remove steak from marinade, letting excess drip away. Discard marinade and let steak sit at room temperature for 30 minutes. This helps the finished product have maximum tenderness.
- GRILL. Preheat grill for direct heat cooking over medium-high heat. Grill steak 4 minutes, turning once halfway through (allowing a good sear to develop before turning). Reduce heat to medium and continue grilling 6 to 8 minutes (cook time can vary depending on steak thickness) or until steak temperature reaches 130 degrees F for medium-rare.
- REST. Transfer to a plate or cutting board and tent loosely with foil for 5 minutes.
- SERVE. Slice thinly against the grain and finish generously with flaky sea salt.
How Long To Marinate Flat Iron Steak
For the best marinated flat iron steak, marinate for at least 4 hours and up to 24 hours.
Four hours allows the seasoning and aromatics to penetrate the meat. An overnight marinade develops even deeper flavor.
While flat iron steak can technically sit longer, we generally avoid going past 24 hours. The acid can begin affecting the texture and make the steak a bit mushy, even after grilling.
Do You Need A Marinade For A Flat Iron Steak?
Technically, no. Flat iron steak is naturally tender thanks to its marbling.
But a good flat iron marinade adds layers of flavor, improves browning and helps create the kind of steak that makes people think you spent much more money than you actually did.
That’s why we almost always marinate this cut before grilling.
Home Chef Tips for Grilled Flat Iron Steak
- Pat the steak dry after marinating. Removing excess moisture helps develop a better crust.
- Invest in an instant read meat thermometer. This is the best, easiest way to check for perfect doneness without slicing into the steak and having its juices seep out.
- We grill our steak to a very rare doneness (120 to 130 degrees F internal temperature when we pull it off the grill), as that’s how our family likes to eat it. If you like it more done, grill until 140 degrees for medium doneness. We don’t recommend going over 140 for good steak.
- No grill? Try a cast iron skillet on the stove.
- Try this marinade for other affordable cuts like top blade steak or butler’s steak.
Make Ahead, Storage And Reheating
- Make Ahead: Blend the marinade up to 3 days ahead and refrigerate in an airtight container. Marinate the steak up to 24 hours before grilling.
- Refrigerate: If you have cooked steak, transfer it to an airtight container and place it in the fridge uncovered for a few hours until it is fully chilled, then cover it with the lid and keep in the refrigerator up to 3 days.
- Reheat: Warm gently in a skillet over low heat or microwave at 50% power until just heated through.
- Freeze: Cool completely, then transfer to an airtight container and store in the freezer for up to 3 months. Thaw overnight in the refrigerator before reheating.
Grilling Flat Iron Steak FAQs
The best flat iron steak marinade balances salt, acidity, sweetness and aromatics. Soy sauce, citrus juice, garlic, onion and a small amount of sugar create flavor without overpowering the steak.
Marinate flat iron steak at least 4 hours and up to 24 hours for the best flavor.
Yes. Overnight marinating works very well and develops deeper flavor.
Yes. For best results, marinate between 4 and 24 hours. Longer than that can negatively affect the texture.
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Grilled Marinated Flat Iron Steak
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Ingredients
- 1 clove garlic roughly chopped
- ¼ small white onion roughly chopped
- ¼ cup vegetable oil
- 2 tablespoons light brown sugar
- 2 tablespoons orange juice
- 2 tablespoons soy sauce
- ½ teaspoon chili powder
- ¼ teaspoon ground cumin
- 1 ¼ pounds flat iron steak
- Flaky sea salt for serving
Instructions
- Place garlic, onion, oil, brown sugar, orange juice, soy sauce, chili powder and cumin in blender and blend until smooth. Makes a heaping 3/4 cup marinade.
- Place steak in shallow baking dish or zip-top bag and pour marinade over steak. Cover and refrigerate at least 4 hours or up to overnight, turning once if possible.
- Remove steak from marinade and allow excess marinade to drip off; discard marinade. Bring steak to room temperature for 30 minutes before cooking.
- Preheat grill for direct grilling over medium-high heat. Transfer steak to grill and cook 4 minutes, turning once halfway through.
- Reduce heat to medium and continue cooking 6 to 8 minutes longer or until center of steak reaches 130 degrees F for medium rare, turning occasionally.
- Transfer steak to plate and cover lightly with foil. Let stand 5 minutes before thinly slicing across the grain.
- Serve steak garnished with flaky sea salt.
