In a large skillet over medium heat, brown the ground beef, breaking it apart with a spatula as it cooks. Drain any excess fat.
Add the chopped onion, green bell pepper, and minced garlic to the skillet. Cook for 3-5 minutes or until the vegetables are tender.
Stir in the tomato sauce, ketchup, Worcestershire sauce, brown sugar, mustard, chili powder, salt, and pepper. Reduce the heat to low and simmer for 10-15 minutes, allowing the flavors to meld together.
Toast the hamburger buns in a toaster or on a griddle until they're slightly crispy.
Spoon the Sloppy Joe mixture onto the bottom half of each bun, then top with the other half.
Serve hot and enjoy the delicious mess!