1/3 c. wine vinegar
1/4 c. catsup
2 tbsp. cooking oil
2 tbsp. soy sauce
1 tbsp. Worcestershire sauce
1/2 tsp. salt
1/4 tsp. pepper
1/4 tsp. garlic powder
1/2 tsp. dry mustard

Combine all ingredients. Place scored flank steak in a plastic bag in deep bowl. Pour in marinade. Marinate 2 or 3 hours in the refrigerator. Cook steak on grill to desired doneness basting with marinade.