1 small onion, chopped

1 small green bell pepper, chopped

1 pound extra-lean (4-7% fat) ground round

2 cups no-salt-added tomato sauce or ketchup

2 tablespoons tomato paste

1 tablespoon prepared mustard

1 tablespoon chili powder

2 teaspoons Worcestershire sauce

1/2 teaspoon salt (omit if using ketchup)

1 tablespoon brown sugar

1/2 teaspoon dried oregano

1/8 teaspoon black pepper

8 (1 1/2-ounce) rolls, split

Heat a large nonstick skillet over medium heat. Add first 3 ingredients; cook until beef is browned, stirring to crumble. Stir in tomato sauce and next 8 ingredients (tomato sauce through black pepper); reduce heat to medium-low. Cover and cook 15 minutes, stirring occasionally. Spoon 1/4 cup beef mixture over bottom half of each bun. Cover with top halves.