Combine all ingredients for the sauce in a bowl and whisk together.
Transfer into a sauce pot and heat it through over medium heat. Lower the heat to medium-low and let it gently simmer for only about 10 minutes. Don’t let it boil!
After you simmer it for a little bit, take it off the heat and serve. (Or store for later use. The sauce tastes even better after a couple of days in the refrigerator.)
Notes
Mustard: for this Carolina gold sauce, DO use a simple yellow mustard! (Don't try to be fancy with Grey Poupon or gourmet mustard, the sauce will be be true.)Other ingredient notes: note that the recipe calls for tomato paste, not tomato sauce. It's not the same! You can use dark or light brown sugar, dark brown sugar just contains more molasses. If you need to substitute apple cider vinegar, use white wine or red wine vinegar, other have a very difference flavor. Make ahead and store: this is a great sauce to make ahead! You can simply prepare it per recipe, store it in the refrigerator once cooled, and use it when needed. It lasts well in the refrigerator for up to 2 weeks and I highly recommend using a glass jar with an air-tight lid to store it.