Place the broth, vinegar, sugar, Worcestershire, and garlic in a 6-quart or larger slow cooker and stir to combine. Generously season the beef all over with salt and pepper. Add to the slow cooker and spoon some of the sauce over top. Cover and cook on the LOW setting until the beef is knife tender, about 8 hours.

Use two forks to shred the beef in the slow cooker, or transfer the beef to a rimmed baking sheet or cutting board to shred with 2 forks. Return the beef to the slow cooker and mix with the sauce.