In a large skillet, saute onions in oil until tender. Add the garlic, pepper flakes and pepper; cook 1 minute longer. Stir in the tomatoes, brown sugar, vinegar, hot pepper sauce, Worcestershire and cumin. Cook over medium heat until sugar is dissolved and heated through.
Cut roast in half. Place in a 5-qt. slow cooker; pour sauce over the top. Cover and cook on low for 10-12 hours or until meat is tender. Remove roast; cool slightly. Skim fat from cooking juices. Shred meat with two forks and return to the slow cooker. Heat through. With a slotted spoon, spoon 3/4 cup meat mixture onto each roll. Yield: 8 servings.