1/4 c. red wine vinegar
2 tbsp. vegetable oil
2 tbsp. soy sauce
2 tbsp. ketchup
1/4 tsp. onion salt (optional)
Garlic powder to taste
Black pepper to taste

Combine ingredients and place with meat into ziploc bag overnight (or at least 6 hours). Broil for 15 minutes or grill outside.