Wash, quarter, clean and cut the apple into slices. Peel onion, cut into rings. Wash liver, dab dry, turn in flour. Fry in hot fat in a coated pan for about 10 minutes.
Season with salt and pepper. Add the apple and onion and fry while turning. Add the sage leaves. Place on a preheated plate and keep warm. Add 1/2 cup of water. Whisk sour cream and cornflour and stir into the stock.
Bring to the boil, season with salt and pepper and add to the apple liver. Stir the flake puree into 1/8 litre of boiling water, also season and arrange on the plate. Sprinkle with nutmeg.