Melt the butter in a saucepan. Finely dice the onion and sauté in the butter over a mild heat until translucent. Deglaze with the white wine, then add the vegetable stock, sauerkraut, bay leaf, juniper berries and possibly caraway seeds. Simmer in a closed saucepan over a low heat for about 20 minutes. Pour in the cream and simmer for another 5 minutes. Season to taste with salt and pepper.