How to Cook a Flat Iron Steak on a Grill

Grilling a steak is an art, and few cuts bring as much satisfaction as the humble yet flavorful flat iron steak. If you’ve never grilled this particular cut, you’re in for a treat. Flat iron steak is tender, juicy, and packed with beefy goodness and when done right on the grill, it rivals premium cuts at a fraction of the price.

In this guide, we’ll walk you through everything you need to know about how to cook a flat iron steak on a grill, from selecting the best cut to serving it up like a pro. Whether you’re a backyard BBQ warrior or a grill newbie, you’ll walk away confident and hungry.

What is Flat Iron Steak?

Flat iron steak comes from the shoulder (chuck) area of the cow, specifically the top blade. Thanks to modern butchering techniques, this cut is separated from the tough connective tissue and transformed into a tender, flat, rectangular piece of meat that’s perfect for high-heat cooking.

With fine marbling and rich flavor, the flat iron is often described as second only to filet mignon in tenderness though it brings a far bolder taste. It’s thinner and broader than cuts like ribeye, making it ideal for quick grilling and fast weeknight meals.

Choosing the Right Flat Iron Steak

Not all steaks are created equal. When shopping for flat iron steak, look for pieces that are around ¾ to 1 inch thick, with even marbling throughout. The marbling is key it ensures the steak remains juicy and flavorful during grilling.

Preferably, opt for USDA Choice or Prime grades. Grass-fed beef offers a deeper, more mineral-like flavor, while grain-fed may have a slightly richer fat profile. If you’re shopping frozen, make sure the steak is vacuum-sealed and shows no signs of freezer burn.

Also, buy steaks of uniform thickness for even cooking. One thick end and one thin end will result in uneven doneness.

Preparing Flat Iron Steak for the Grill

Once you’ve brought home your steak, it’s time to prep it for grilling. If your steak has a bit of silver skin or excess fat, trim that off with a sharp knife. While fat can add flavor, silver skin doesn’t render down and can cause the steak to curl or chew poorly.

Pat the steak dry with paper towels. This is a simple but crucial step removing moisture from the surface helps the steak sear instead of steam when it hits the hot grill.

Marinating or Seasoning Options

Marinade Magic

Flat iron steak does well with a marinade, especially since its relatively loose grain allows the flavor to penetrate easily. A good marinade might include:

• ¼ cup olive oil
• 2 tablespoons balsamic vinegar or soy sauce
• 2 cloves garlic (minced)
• 1 teaspoon Dijon mustard
• Fresh thyme or rosemary
• Salt and pepper

Marinate the steak in a zip-top bag or covered dish in the fridge for at least 30 minutes, up to 2 hours. Avoid going longer too much acid can begin to break down the meat excessively.

Simple Dry Rub

Prefer to keep things fast and bold? A dry rub is your best friend. Here’s a classic rub blend:

• 1 tablespoon kosher salt
• 1 tablespoon black pepper
• 1 teaspoon smoked paprika
• 1 teaspoon garlic powder
• ½ teaspoon onion powder

Rub it evenly over the steak and let it sit at room temperature for 20–30 minutes before grilling. This gives the seasoning time to adhere and the steak time to warm up slightly for even cooking.

Preheating and Setting Up the Grill

Whether you’re working with a gas or charcoal grill, preheating is non-negotiable. Aim for a medium-high heat about 400–450°F. This ensures a beautiful sear and grill marks without overcooking the steak.

Gas Grill

• Turn on all burners to high and close the lid for about 10–15 minutes.
• Once heated, reduce to medium-high.
• Optionally, turn one burner to low to create a cooler indirect zone.

Charcoal Grill

• Fill your chimney starter with charcoal and light it.
• Once the coals are ashed over (around 15 minutes), dump them onto one side of the grill for a two-zone setup.
• Place the grill grate on and let it preheat for 5 minutes with the lid closed.

Grilling the Flat Iron Steak

Now for the fun part grilling the steak!

Step-by-Step:

1. Oil the grates – Use a paper towel dipped in oil and long-handled tongs to coat the grates. This prevents sticking and promotes searing.
2. Place the steak over direct heat – Lay the steak diagonally across the grates. Don’t move it for the first few minutes.
3. Grill time:
   • Grill for 4–5 minutes per side for medium-rare (depending on thickness).
   • Flip only once to retain juices and get a solid sear.
4. Use a meat thermometer to check internal temperature:
   • Rare: 120–125°F
   • Medium-rare: 130–135°F
   • Medium: 140–145°F
   • Medium-well: 150–155°F
   • Well-done: 160°F+
5. Optional: If your steak is browning too fast, move it to the indirect heat zone to finish cooking.

Avoid pressing the steak with your spatula this squeezes out those flavorful juices you worked so hard to keep inside.

Resting the Steak

Once your steak hits the target temp, remove it from the grill and place it on a cutting board. Tent it loosely with foil and let it rest for 5–10 minutes. This allows the juices to redistribute throughout the steak, making every bite juicy and flavorful.

Skipping this step will result in a dryer steak even if it was cooked perfectly.

Slicing and Serving

Flat iron steak, like most cuts, should always be sliced against the grain. You’ll notice the muscle fibers run lengthwise cutting across them shortens the fibers and makes the steak more tender to chew.

Use a sharp slicing knife and cut into thin, clean strips. Serve the steak with your favorite sides:

• Grilled asparagus
• Roasted potatoes
• Chimichurri sauce
• Garlic butter mushrooms
• Caesar salad
• Corn on the cob

The rich, beefy flavor of flat iron pairs beautifully with bold sauces and seasonal vegetables.

Common Mistakes to Avoid

Even experienced grillers can slip up. Avoid these pitfalls:

• Overcooking – Flat iron is best enjoyed medium-rare to medium. Going beyond that can make it tough.
• Skipping the rest period – Resting is critical to maintaining juiciness.
• Failing to preheat the grill – A hot grill ensures caramelization and locks in flavor.
• Not slicing against the grain – This small detail has a huge impact on tenderness.

Final Tips for the Best Grilled Flat Iron Steak

• Invest in a meat thermometer – It’s the best way to guarantee perfect doneness.
• Use compound butter – A pat of garlic herb butter on the resting steak adds richness.
• Add wood chips – For charcoal grilling, toss in hickory or mesquite chips for smoky depth.
• Grill in batches – Don’t crowd the grill; give each steak room to breathe and brown.
• Experiment with toppings – Crumbled blue cheese, sautéed onions, or even grilled peaches make exciting additions.

Conclusion

Flat iron steak may not always be the star of the butcher’s counter, but it’s a hidden gem that delivers big on flavor, tenderness, and versatility. When grilled to perfection, it becomes the centerpiece of a memorable meal that feels like fine dining right in your backyard.

By choosing the right cut, seasoning it properly, mastering the grill, and slicing with care, you can unlock the full potential of this underrated steak. Fire up that grill, grab your tongs, and treat yourself to a steak night done right.