Return the cooked sausages and bacon to the pan with the onions. Stir in the mushrooms, their soaking liquid, and the prunes. Cover the pot and let it cook for another 20 minutes.
Now, add the bay leaf, cloves, peppercorns, juniper berries, and allspice berries. Pour in the 90 ml red wine and 2 tbsp tomato purée. Bring the mixture to a gentle simmer, then cover again and cook for another 1 hour. The stew should be thick and deeply colored.
Season the bigos well with salt and pepper to taste. Let it cool completely before covering and chilling. This stew keeps well in the fridge for up to two days, and many cooks find its flavors deepen and improve over that time. Reheat until it's steaming hot all the way through before serving.