2 tbsp. Worcestershire sauce
1 tbsp. soy sauce
2 garlic cloves, minced
1/8 c. red wine vinegar
2 tbsp. olive oil
1/4 tsp. dry mustard
1/4 c. ketchup
1/4 tsp. fresh ground pepper

Mix all ingredients together and chill for 6-24 hours. Pour 1/2 of the marinade on an 8 1/2 x 11 inch cookie sheet, then put burgers on the cookie sheet. Baste top of burgers with remaining marinade sauce and let burgers sit in the refrigerator for 15-20 minutes uncovered. Grill 1 1/2 to 2 1/2 minutes on each side on a preheated grill.