1/3 c. wine vinegar
1/3 c. cooking sherry
1/4 c. catsup
2 tbsp. oil (Crisco, corn, etc.)
2 tbsp. soy sauce
1 tbsp. Worcestershire sauce
1 tsp. prepared mustard
1 tsp. salt
1/4 tsp. pepper
1/4 tsp. garlic powder

Mix all ingredients and pour over roast. Turn roast over in sauce and cover all sides. Cover with plastic wrap and refrigerate overnight or several days. Bake in slow oven (325 degrees).