Heat the oil in a large, heavy-bottomed frying pan. Add the pancetta and fry until brown and crisp. Remove from the pan and add to a large stock pot or casserole dish.
Fry the shin of beef in the frying pan, on both sides, until well browned. Transfer the shin to the stock pot.
Pour the red wine into the frying pan and stir, for 2-3 minutes to collect the cooking juices. Tip into the pot.
Place the stock pot over a gentle heat. Add the carrots, celery and onions. Pour in the tomato purée and enough stock or water to cover the meat and vegetables. Add the bouquet garni and cover with a lid.
Simmer for 3-4 hours, stirring occasionally. Serve with mashed potato.