We didn't cover the subject of sauces because most "professionals" believe if you've used the right fuel, the right rub and the right temperature, there is no need for a sauce. They may be right, but the majority of Americans just gotta have their barbecue sauce.
It seems each region of the country has their own "only true" barbecue sauce. Here in the Carolinas there is the vinegar based sauce which is nothing more than vinegar, salt and red pepper flakes of eastern North Carolina to the tomato based sauce of western Carolina and even a mustard sauce popular in the upstate of South Carolina. I've come up with what I call the "Carolina Comprise". It is a compromise between the all vinegar sauce and the tomato sauce.
Yield: 1 Gallon - Cooking Time: Approx. 1 1/2 Hrs
Sauté onion in oil until tender but not browned. Add all remaining ingredients and mix thoroughly. Bring to a boil; reduce heat and simmer uncovered 1 to 1 1/2 hrs.
Puree in batches in either blender or food processor and then cover and store in refrigerator for at least two days before use.
(May also be used as a mopping sauce.)