The margarine is melted in a saucepan and the sliced onions are roasted in it. Now add the sauerkraut, the letscho and the fish fillet cut into pieces. Top up with vegetable stock until everything is covered with liquid. The pickles are cut into small cubes and added with a bay leaf, salt and squeezed garlic. Let the soup simmer for 10 minutes.
Season to taste with salt, lemon juice and sour cream before serving.