1. In a medium skillet, heat oil over medium-high heat, cook beef until brown. Drain most of the fat and discard.
2. Add onion, garlic and red bell pepper, cook for about 5 minutes, until onions are translucent.
3. In a separate bowl, combine ketchup, mustard, brown sugar, Worcestershire sauce, vinegar and cayenne pepper.
4. Add the mixture to the meat, stir to combine. Reduce heat; cover and simmer for 30 minutes.
5. Using a spoon, put the Sloppy Joe mixture onto toasted bun bottoms (you can melt a slice of cheese over the top or over the bun bottoms). Cover with bun tops and serve.