1. Heat oil in a large frying pan set over medium-high heat. Cook onion and pepper for 5 minutes
2. Add beef to the pan. Cook, stirring until browned, about 5 to 10 minutes then drain off fat.
3. Stir in ketchup, brown sugar, Worcestershire sauce, salt and pepper. Simmer over medium-low heat, stirring occasionally, for 10 minutes or until slightly thickened. Serve on sandwich buns.