In a glass dish, combine oil, soy sauce, honey, onion and ginger; mix well.
Pierce flank steak with a fork and place in marinade. Refrigerate overnight. Preheat grill.
Drain steak, discarding marinade. Grill over hot coals for 10 to 15 minutes on each side, to the desired degree of doneness. Slice thinly against the grain to serve.
Servings: 4