Since it's a long, flat steak, there's a lot of surface area to develop an outstanding crust, but this shouldn't be done at the expense of overcooking the inside. The solution is a blazing hot fire to sear the steak quickly before it cooks all the way through.

• Preheat grill to 450-500°F.
• Pat the steak dry, season it, and place it on the grill.
• Sear it on each side for 3-5 minutes until about 130°F for medium-rare.
• Remove from the grill and let it rest for 3-5 minutes before slicing against the grain.

See also Grilled Flat Iron Steak