North Carolina Barbecue Sauce

Melt the butter in a saucepan over medium heat. Add the onion and cook, stirring frequently, until the onion is soft, about 3 minutes.

Add the vinegar, mustard, brown sugar, ketchup, Worcestershire sauce, chili powder, cayenne, and black pepper. Mix well.

Bring the barbecue sauce to a boil then reduce the heat to a low simmer. Let simmer, uncovered, for 30 minutes or until the sauce has thickened.

Season as needed with salt and pepper. Let the sauce cool to room temperature before using or storing in an airtight container in the refrigerator.