Use a 6-quart slow cooker. Put the butter into the bottom of the slow cooker and turn on. Swirl the meat, onion rings, and garlic around in the melting butter. Add the sugar and pepper. Then stir in the broth, beer, sherry, and Worcestershire sauce.

Cover and cook on low for 7 hours or until the meat is tender to bite and has begun to lose shape and fall apart. Serve on gluten-free toasted soft rolls with slices of provolone or Swiss cheese. Dip sandwiches into the accumulated broth for a traditional French Dip Sandwich experience.