Preheat oven to 275 and line a baking sheet with foil. Top with a wire rack.
In a small bowl, combine brown sugar, paprika, garlic powder, onion powder, salt and pepper and mix well. Slice the pork belly into large, 2" chunks and dredge all sides in the seasoning, generously coating it.
Place fat side up on to the rack on the baking sheet. Keep pieces separate, and not touching.
Bake for 3 hours. Remove from oven and increase heat to 350 degrees. Top each piece with a brush of barbecue sauce and return to oven for 10 minutes or until sauce is hot and caramelized. Let rest for 10 minutes before serving.