Peel and chop the onions. Heat the oil in a casserole. Sauté onions in it, add sauerkraut. Pluck apart with a fork. Dust with paprika and deglaze with cream.
Bring to the boil, season with salt, pepper and sugar. Cover and stew at low heat for 18-20 minutes. Wash fish and pat dry. Mix flour, salt and pepper. Whisk eggs. Turn fish first in flour and then in egg.
Heat clarified butter in a large frying pan. Fry the fish for 3-4 minutes on each side. Wash parsley, shake dry, chop finely and mix into the cabbage. Arrange cabbage and fish on plates.
Garnish with parsley.