This is Carolina style barbecue. This means that it is vinegar and mustard based, as opposed to the ketchup and molasses based sauces of the mid and southwest. The combination of sweet and tangy flavors brings out the absolute best in grilled or smoked pork or chicken.
South Carolina has four distinct regions/styles of BBQ: Vinegar & Pepper, Tomato, Ketchup, and Mustard. Charleston is split between mustard and vinegar.