Heat a frying pan over high heat and sear the diced beef until browned. Transfer the beef to the slow cooker, leaving the fat in the pan.
Add sliced sausage to the same pan and continue frying until browned, then transfer it to the slow cooker.
In the same pan, sear the diced onions, carrots, and garlic until they are softened and lightly browned. Transfer them to the slow cooker as well.
Add all the remaining ingredients to the slow cooker and stir well to combine. Cover with a lid and set the slow cooker to high heat for 6 hours. After the first hour, give it a good stir and repeat every hour or so to distribute the flavours.
When the Bigos is ready, remove the bay leaves and serve hot with buttered sourdough bread.
Day two is better again. Let it cool, cover it and refrigerate it overnight, then reheat it on the hob until it is bubbling right through before serving. It keeps in the fridge for up to four days. Do not reheat it from cold in the slow cooker, which takes too long to bring it up to temperature.
Notes:
Why a slow cooker. Bigos catches on the bottom of a pot. On the hob you are tied to the kitchen, stirring every half hour, and if it catches even once that burnt taste runs through the whole batch. A slow cooker has no hot spot, so there is nothing to scorch and nothing to stir. A heavy pot on the hob or a low oven works too, but keep the heat as low as it will go and stir regularly.Salt last, if at all. No salt goes in at the start here, and that is deliberate. Undrained sauerkraut, beef stock and kielbasa bring plenty between them. Taste it at the end and season then, when you can judge what is actually in the pot.On freezing. Unlike my Bigos Królewski, this one has potatoes in it, and potatoes turn grainy once they have been frozen in liquid. If you want a batch for the freezer, lift the potatoes out first, or leave them out and boil fresh ones on the day.It is already a full meal. The potatoes cook in the pot, so nothing needs to be served alongside. Bread is worth having to mop the bowl, and a spoonful of soured cream on top is good, but you do not need to cook a side.