Place the meat in a dish and cover with a mixture of 1 part vinegar to 16 parts water. Refrigerate.Leave overnight if possible or for at least 2 hours. Remove, wash well and flavour with salt and pepper. Leave for about 1/2 an hour.

Cut the meat into small pieces and flour lightly on both sides. Brown gently in a pan with oil. Remove meat and fry the onions, sliced, until golden brown. Add the tomatoes, peeled and chopped, and fry until cooked. Add the garlic, finely chopped and fry until soft. Stir the tomato puree or paste into the mixture, adding a little water to create a smooth liquid sauce. Add sugar and salt and pepper to taste. Place the meat in the sauce and simmer for 1/2 hour. Add a glass of red wine, if desired and continue to cook until tender.

Serve with pasta and parmesan cheese or a mixture of roast vegetables.