Marinate:

Cup of Yum
1. In a resealable plastic bag, combine the lime juice, soy sauce, scallions, ginger, and red pepper. Add the steak and seal the bag.
2. All-day marinating: refrigerate for 8-12 hours. I like to place the bag in a baking dish to catch any possible leaks. 30 minute method: place the bag on the counter for up to 30 minutes, especially if the beef is cold from the fridge so it comes to room temperature before cooking.

Cook:

1. Remove the marinated meat from the refrigerator while you preheat the grill.
2. On the grill: heat the grill to high, about 400F if it has a gauge. Soak a paper towel in oil and use tongs to brush it against the grates and grease them. Remove the steak from the marinade, letting excess drip off into the bag. Place the steak on the grill, close the lid, and cook for 8 minutes (for medium-rare to medium), flipping it over once after 5 minutes. Check the temperature and remove from the grill onto a board. Wait 10 minutes before slicing it against the grain.
3. In a pan: heat a large cast iron or stainless steel pan over medium-high heat. Add some oil to the pan and distribute it around. Place the flank steak on the very hot pan and let it sear in place, without moving it, cook it for 3 minutes. Use kitchen tongs to flip it over and sear the second side for another 3 minutes. Turn off the heat and let it sit in the hot pan for 3 more minutes to finish cooking with the residual heat. Check for doneness. Remove from the pan onto a board and wait 10 minutes before slicing.