1Heat oil in 1-quart saucepan over medium heat. Cook onion in oil 2 minutes, stirring frequently. Stir in red pepper, garlic and salt; reduce heat to low. Cover and cook 5 minutes, stirring occasionally. Stir in chocolate until melted.
2Pour water, vinegar and tomato paste into food processor or blender. Add onion mixture and sugar. Cover and process, or blend, until well blended.
3Heat oven to 375°. Cut between pork back ribs to separate. Place in single layer in roasting pan. Pour sauce evenly over pork. Bake uncovered 30 minutes; turn pork. Bake 45 to 55 minutes longer or until ribs are tender.