Salt fish, chop, pepper, grease with vegetable oil, lay on a baking sheet.
Boil mushrooms in salted water, cool, cut.
Cut onions and fry with mushrooms with flour.
Mix sour cream with water, salt and spices, add to the mushrooms and cook until thick.
Put the fish in the oven for 15 minutes at 220 degrees. Then get, pour sauce, sprinkle with cheese. Bake another 15 minutes.