This is a toned-down version of the bracing North Carolina Vinegar-based BBQ sauce. Most folks don't like it as much as more traditional sugar, molasses and tomato sauces, but it grows on you.
1 c. cider vinegar
1/2 c. ketchup
1/2 c. water
1/4 c. sugar
1 tsp. salt
1 tsp. ground black pepper
1/2 c of liquid from oven smoked pork, or 1/2 c. beef broth
Combine all ingredients in a saucepan. Bring to boil, turn off and serve.