In a large frying pan cook the sausages until brown, then remove them from the pan.
Add the onions to the pan and lightly fry until soft. Then add the tomatoes, tomato purée, red wine, casserole mix and salt and pepper to taste. Stir well and leave to come up to the boil.
In the meantime chop the sausages into bite size pieces and once the sauce has come to the boil, turn down the heat to a simmer and add the sausages. Stir well and make sure the sausages are covered in the sauce.
Leave it on a low heat and serve when the sausages are cooked or when you're ready to eat. I made cheesy mash potato to serve with it, very nice!
You could add other ingredients such as carrots or mushrooms to make a heartier meal, just experiment :o)