Butter one side of each piece of bread and set aside.
Over medium heat, add oil, onion, pepper and beef in a small pan and cook for 2-3 minutes or until heated through. Stir in hot sauce and season with salt and pepper
Place 1 piece of bread, butter side down into a small frying pan. Add 1 slice of cheese and top with beef mixture. Add another slice of cheese and top with another piece of bread, butter side up. Heat over medium low heat, until both sides are grilled and cheese is melted.