Flat iron steak, when cooked properly, turns out tender and juicy. This steak is generally nicely marbled which makes it especially rich and flavorful. Because of its muscular structure, it is best if it isnÃ¢â‚¬â„¢t cooked beyond medium or medium-rare (135 F). High heat and short cooking time on the grill or skillet work best. Feeling a bit adventuresome? Flat iron steaks love spice rubs and marinades! We like this one ourselves: Red Wine Marinade 2 (about 1 pound) flat iron steaks 1/4 cup of dry red wine 1 to 2 cloves garlic (minced) 3 tablespoons olive oil 1 teaspoon fresh thyme (chopped) 1/2 teaspoon fresh rosemary (chopped) 1 teaspoon dry mustard 2 teaspoons sea salt Place flat iron steaks in a shallow baking dish. Season with salt. Combine marinade ingredients and pour onto meat, turn to coat, and cover with plastic wrap. Allow to marinate in the refrigerator for 1 hour.Preheat grill for medium-high heat. Remove meat from the dish and discard marinade. Place onto the grill and cook for 6 to 8 minutes per side. Enjoy!