Place short ribs in slow-cooker. In medium bowl, combine mustard, garlic, honey, salt, pepper, and barbecue sauce. Pour over ribs. Cover and cook on Low 6-7 hours or until tender. Refridgerate several hours or overnight. Skim any solidified fat from top. Remove ribs; heat in microwave or conventional oven. Dissolve cornstarch in water. Add to sauce. Cook and stir in microwave or stovetoo until hot and slightly thickened. Pour hot sauce over warm ribs.
