Add egg, add salt, zero milk, constantly add flour and stir until it is empty and then add the vegetable oil and bake cookies. Boil potatoes, mash, salt and pepper to prepare the core. Sprinkle onion, fry in vegetable oil, then add sliced mushrooms and continue to fry. After that, add potatoes, sour cream and cook for 7-10 minutes on a weak fire. Ready to be cool. Put the bowl in a bowl with a spoon, wrap and fry with butter.