I use the marinade below (this amount of marinade is for 1.5 pounds of meat)
1/3 cup soy sauce
3 tablespoons Worcestershire sauce
1 tablespoon balsamic vinegar
2 tablespoons vegetable oil
4 cloves garlic, crushed
1 teaspoon sugar
Freshly ground pepper
I use flank steak, skirt steak or flap steak. (I usually buy from Costco but any place is good).
I put the marinade on the steak and let it marinade for 3-4 hours or overnight in refrig,
Take out for 30 min before grilling.
We heat the grill up to high (500 deg,) and grill for 4 minutes on each side, 6, minutes for thicker flank steak.
After it is done cooking, remove to a cutting board or plate, put aluminum foil over it and allow it to rest for 5-10 minutes, ( 20 min for thicker flank steak) then cut on the bias