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