1/2 c. vegetable oil
1/3 c. soy sauce
1/4 c. red wine vinegar
2 tbsp. lemon juice
1 tbsp. Worcestershire sauce
1 tsp. dry mustard
1/4 tsp. pepper
1 1/4 lb. flank steak

Combine all ingredients except steak in glass or ceramic dish. Add steak and turn to coat with marinade. Marinate, loosely covered, for at least 4 hours or overnight (overnight is best). Grill about 5 minutes on each side (over hot coals or high on gas grill) or until browned on outside but still rare in center. Cut steak diagonally across grain into thin slices. Serves 3-4.