Preheat the oven to 170°C, 150°C fan, 325°F, Gas Mark 3.
Rinse the sauerkraut in a sieve under plenty of running water.
Heat the oil in a large casserole with a lid. Brown the bacon and sausage all over, until they begin to give up their fat and turn golden. Remove to a large bowl with a slotted spoon and set aside.
Toss the pork shoulder with the flour and season well, shaking off any excess flour. Add to the pan and brown on all sides. Transfer to the bowl with the bacon and sausage.
Add the onion, carrots, sauerkraut, cabbage and fresh mushrooms to the casserole, turn down the heat and cook gently for 10 minutes, until soft but not browned.
Add the red wine and scrape at the base of the pan with a wooden spoon. Now add the tomato purée, oregano, caraway, bay leaves and dried mushrooms. Cook, stirring for 2 minutes. Return the meat and any collected juices to the casserole with the beef stock and tinned tomatoes. Bring to the boil, cover and transfer to the oven for about 3 hours, until the meat is very tender.
Freezing and defrosting guidelines
Cook as instructed and allow to cool completely. Then transfer to an airtight, freezer-safe container, seal and freeze for up to 1-3 months. To serve, defrost thoroughly in the fridge overnight before reheating. To reheat and serve, place on medium heat, stirring occasionally until the dish is heated through.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.