In a plastic bag combine the lime juice, soy sauce, green onions, ginger and red pepper flakes.
1/3 cup lime juice, 2 Green Onions, 2 tablespoons soy sauce, 2 tablespoons Ginger, 1/2 teaspoon crushed red pepper
Using a sharp knife lightly score the steak in a cross-hatch pattern on both sides.
1 1/2 - 2 pounds flat iron steak
Place the steak in the marinade filled Ziplock bag. Press out all of the air and seal. Place the bag in a dish to protect against leakage. Place the bag in the refrigerator. Marinate for at least 30 minutes or longer. 12 to 24 hours is plenty of time to marinate the meat. If the steak is left in the marinade for longer it can result in over tenderizing the meat.
Heat a grill pan to medium heat. Lightly oil the pan. If grilling the steak then heat up the grill and lightly oil the grill grates.
Remove the steak from the marinade and let the excess marinade drip off. Pat dry with a paper towel.
Season to taste with salt and pepper if desired. Place the steak on the grill pan, cover and cook for 3-5 minutes. Turn the meat and cook until the meat has reached the desired doneness, about 3-4 minutes (depending on thickness of steak) for medium rare.
Salt and Pepper to taste