Begin by placing the sliced white cabbage into a sturdy, heavy casserole dish. Pour in the beef stock, then set the pot over low heat, allowing the cabbage to gently simmer for approximately 50 minutes, or until it becomes tender and infused with the rich stock flavors. This slow cooking will soften the cabbage perfectly, forming a comforting base for the stew. While the cabbage cooks, prepare your mushrooms by soaking them and then slicing into strips, carefully reserving the soaking water to capture all the earthy mushroom essence. In a separate pan, heat the lard and fry the German sausages and bacon until browned and fragrant. Once cooked, remove the meats from the pan, leaving the delicious rendered fat behind, which will add depth to the onions. Next, sauté the chopped onions in the leftover fat over medium heat for 5 to 8 minutes, until they develop a light golden brown color, adding a subtle sweetness to the stew. Return the sliced mushrooms with their soaking liquid to the pan, then add the cooked meats, sautéed onions, and prunes, stirring to combine these rich, hearty ingredients. Cover the casserole and let these flavors meld together over 20 minutes of gentle cooking. Then, stir in the fragrant spices — bay leaf, cloves, peppercorns, juniper berries, and allspice berries — along with the red wine and tomato purée. Bring the mixture to a delicate simmer, then cover again and continue cooking over low heat for one hour. This slow simmer allows the flavors to deepen and mingle beautifully. After cooking, season the bigos well with salt and pepper to taste. It's important to let the stew cool before storing; bigos keeps well refrigerated for up to two days and actually tastes even better the next day, as the flavors have time to develop fully. When ready to serve, gently reheat the stew until it is piping hot, ensuring the hearty, comforting flavors are at their best.