Add ground beef to a large Dutch oven set over medium-high heat. Cook the beef for 5-6 minutes, crumbling it as it cooks, until it begins to brown. Drain off any excess fat.
Reduce the heat to medium, then add the green pepper, onion, and garlic and cook for 3-4 minutes, stirring occasionally, until the vegetables are softened.
Stir in the diced tomatoes, tomato sauce, Worcestershire sauce, and sugar. Bring the mixture to a boil, reduce the heat, cover, and simmer for at least 20-25 minutes.