Shredded Beef Sandwich

Ingredients:
3 pounds beef stew meat, cut into 1 inch cubes
3 medium green peppers, diced
2 large onions, diced
1 (6 ounce) can tomato paste
1/2 cup packed brown sugar
1/4 cup cider vinegar
3 tablespoons chili powder
2 teaspoons salt
2 teaspoons Worcestershire sauce
1 teaspoon ground mustard
14 sandwich buns, split

Directions:
In a 6-qt. slow cooker, combine the beef, green peppers and onions. In a small bowl, combine tomato paste, brown sugar, vinegar, chili powder, salt, Worcestershire sauce and mustard. Stir into meat mixture. Cover and cook on high for 7-8 hours or until meat is tender.
Skim fat from cooking juices. Shred beef, using two forks. With a slotted spoon, place about 1/2 cup beef mixture on each bun.