Pour marinade over flank steak, turning it so it is fully covered in the marinade.
Cover with plastic wrap and refrigerate at least 2 hrs to overnight for best flavor.
Preheat the grill on high heat.
Remove the steak from the marinade and sprinkle it with coarse salt and freshly ground pepper.
Place the steak on the hot grill and brown it for about 2 minutes on each side. Move the steak to a cooler spot on the grill (spot with indirect heat), and continue cooking until done to your liking. (rare: 120 F internal temperature, medium-rare: 130 F internal temperature, medium: 140 F internal temperature, medium-well: 150 F internal temperature, well done: 160 F internal temperature)
Let the steak rest for 5 minutes before cutting it against the grain. Serve with grilled veggies or a side salad.
Notes
If the pan or grill is not hot enough, the steak might stick to it. To prevent this from happening, spray your pan or grill with a little non-stick spray.