Cut the meat and sausage into 2 in / 5 cm chunks. (You can toss in flour if you want to thicken the stew.) Fry the onions in the oil until nicely browned, and brown the meat in the same pan. A large, heavy, lidded flameproof casserole is best. Cut up the ceps and add them to the pan with their soaking liquid, the sauerkraut, spices, bay leaf, dill seeds and prunes. Rub the tomatoes through a sieve, and stir into the mixture. Add enough water or stock to cover all the ingredients, bring to the boil and simmer very gently for about 1½ hours. Alternatively, cook in a preheated oven at 150°C / 300°F / Mark 2. Uncover for the last 20 minutes to let the liquid evaporate as the stew should be fairly thick. Season with pepper, stir in the soured cream, if using, and serve the stew from the pot, brightened up with the dill or parsley, if liked. Baked potatoes go very well with this, as does rye bread. Beer or ice-cold vodka are the perfect accompaniments.