Melt the butter in a large frying pan over a medium heat, then add the onion and green pepper. Fry until softened and just starting to pick up colour, then add the garlic and fry for another 1–2 minutes. Add in a teaspoon of oil if the pan dries out.
Add the beef and fry until browned, breaking it up with a wooden spoon as you go. Stir in the tomato purée and fry for another couple of minutes.
Pour in the passata and water. Stir in the ketchup, mustard, Worcestershire sauce, brown sugar, salt and pepper.
Lower the heat and simmer gently for 20–25 minutes, or until nice and thick, stirring occasionally as you go.
Check seasoning and adjust with salt and pepper. Spoon into buns or rolls, then serve and enjoy!
