2) Add the meat to the pan, increase the heat to medium, and cook the meat, breaking it up with a wooden spoon, until it just loses its colour, about 5 minutes. Pour excess fat from the pan and discard.
3) Combine the meat and vegetables in the pan along with the tomato sauce, sugar, Worcestershire sauce, vinegar, mustard, and 125ml of the water. Bring the mixture to a simmer, cover, and cook for 20 minutes. (If the mixture appears to be too dry add the additional water.) Season with the salt and pepper to taste.
4) When ready, divide the mixture evenly between the buns and serve.