Place garlic in 4- to 5-quart slow cooker. Place beef on garlic. Pour vinegar over beef.
Serve one-third of the beef now. Cut remaining beef into thin slices. Place 2 cups sliced beef in each refrigerator or freezer container. Add 1/2 cup reserved beef juices to one container for Italian Beef Sandwiches and 1/4 cup reserved beef juices to the other container for Beef and Broccoli Stir-Fry. Cover and refrigerate beef up to 4 days or freeze up to 4 months. To thaw frozen beef, place container in refrigerator about 8 hours.
Substitution: Red wine vinegar can be used instead of balsamic vinegar.