1. Trim fat from roast. If necessary, cut roast to fit into a 3 1/2- or 4-quart slow cooker. In a large skillet, brown roast on all sides in hot oil.
2. In the cooker, combine carrots, celery, onion, and garlic. Sprinkle tapioca over vegetables. Arrange roast to cover vegetables.
3. In a medium bowl, combine undrained tomatoes, tomato paste, brown sugar, salt, pepper, and bay leaf; pour over the roast in cooker.
4. Cover and cook on low-heat setting for 10 to 12 hours or on high-setting for 4 to 5 hours.
5. Discard bay leaf. Skim off fat. Slice meat. Serve with hot cooked noodles. If desired, garnish with celery leaves.