Wash the mushrooms and soak in 1/8 litre warm water. Peel onion, dice finely and fry in 2 tablespoons of hot fat until translucent. Add sauerkraut. Add 1/8 l water, bay leaves and juniper berries and braise for about 20 minutes.
Add mushrooms and soaking water and cook for another 20-25 minutes. Season sauerkraut with salt, pepper and sugar. Knead remaining fat and flour. Bring the cabbage to the boil again, stir in flour-butter and cook for another 5 minutes