In a large skillet coated with cooking spray, heat oil over medium-high heat. Add onion; cook and stir 2-3 minutes or until tender. Stir in tomatoes, vinegar, peppers with sauce, garlic, brown sugar, bay leaves and spices. Bring to a boil. Reduce heat; simmer, uncovered, 4-6 minutes or until thickened., Place roast in a 5-qt. slow cooker; add tomato mixture. Cook, covered, on low 8-10 hours or until meat is tender., Discard bay leaves. Remove roast; cool slightly. Skim fat from cooking juices. Shred beef with two forks. Return beef and cooking juices to slow cooker; heat through. Serve with rice. If desired, top with cheese and sour cream.