In a medium saucepan, combine vinegar, ketchup, brown sugar, molasses, yellow mustard, Worcestershire, garlic, salt, red and black peppers. Bring mixture to a simmer, stirring to dissolve the sugar. Allow sauce to simmer for 10 to 15 minutes, or until slightly thickened. Set aside to cool.
Place a pizza stone on the lowest rack of the oven and preheat to 500 degrees F.
Sprinkle about 2 to 3 tablespoons of yellow cornmeal on a baker's peel or baking sheet. Place the rolled out pizza dough on the prepared baker's peel or baking sheet.
Spoon 1 cup of the cooled barbecue sauce over the pizza dough, leaving about 3/4-inch of dough uncovered around the edge. Spread the pulled pork over the sauce, then top with the onion slices and chopped bell pepper. Spread the cheeses evenly over the top. Using a quick flick of the wrist, slide the prepared pizza onto the hot pizza stone and bake for 10 to 12 minutes, or until the crust is crisp and golden and cheese is melted and bubbly. Serve with remaining barbecue sauce, if desired.
Yield: 1 large 15-inch pizza, serving 4 to 6