- chopped onion, or more to taste
- Can tomato sauce
- Brown sugar
- Chili powder
- Soy sauce
- Dry mustard
- Boneless beef chuck roast
- Stir onion, tomato sauce, brown sugar, vinegar, chili powder, soy sauce, salt, and mustard together in a slow cooker;
- Add roast. Spoon onion mixture over the beef to coat.
- Cook on High for 7 hours.
- Shred meat in slow cooker with a pair of forks. Continue cooking 1 hour more.