I ran across a sauce recipe that I thought lost, it’s a copycat recipe for a sauce that a local, long gone BBQ joint made and sold:

2 cups vinegar
2 cups water
2 cups sugar
1/3 cup cornstarch
1 tsp salt
3 tsps ground black pepper
1 tsp cayenne pepper
8 oz can tomato sauce

The pepper amounts are suggestions for a relatively mild, sweet sauce. I used more ground black pepper, more cayenne, and added some finely ground Sichuan peppercorns. Not sure what vinegar to use, I went with 1 cup of white, and 1 cup of cider. Either kind will work. I used a ketchup squeeze bottle to hold it all. I keep it in the fridge, not sure it needs it.