Grilled London Broil

1 (1 1/2-pound) flank steak
1/3 cup vinegar
1/3 cup vegetable oil
3 tablespoons brown sugar
3 tablespoons soy sauce
2 medium onions, sliced
2 cloves garlic, crushed

Place steak in shallow glass dish. Scatter onions on top and underneath steak. Mix remaining ingredients; pour over steak. Cover dish with plastic wrap and refrigerate at least eight hours, but preferably overnight, turning steak occasionally.

Remove steak from marinade. Grill steak on barbecue grill or under broiler until preferred doneness is reached. At the same time, heat up marinade with onions, letting it simmer until onions are semi-soft.

To serve: Cut meat diagonally across the grain into very thin slices; serve with onions and marinade.

Serves 4.

NOTE: This marinade is also excellent using chicken or thick pork chops instead of the flank steak. Discard unused marinade.