I usually serve my vinegar sauce on the side, and my BBQ sauce on the side as well. Choices for the audience. Here's my vinegar sauce:
1 cup cider vinegar
2 tbs brown sugar
1 tsp cajun seasoning
1 tsp coarse black pepper
1 tsp red pepper flakes
1 tsp kosher or sea salt
1 tsp hot sauce (I like Secret Aardvark)
Warm the vinegar enough to dissolve the sugar, add/whisk in the remaining ingredients and mix thoroughly.
Of course, you can raise or lower ingredient levels to your taste.