Though it may often be very basic, many barbecue experts swear by vinegar sauce. Thinner and tangier (and sometimes very hot) its combination of red pepper flakes and vinegar is meant to be basted on meat and perfectly compliment the smoke of the grill and the fat of the pork. The debate rages, however, over whether or not to add a little tomato paste or ketchup. In Eastern North Carolina and other areas, pit masters let red pepper rule. To the west, many prefer the style made popular in the famed barbecue center of Lexington, N.C., where it is felt the sweetness of the tomato adds a necessary touch.