Wash the carp inside and out under cold water, pat dry, season with salt, pepper and place in a pan with butter. Fry in a preheated oven (200 ° C) halfway done (bubbles must form under the skin), and occasionally baste with frying fat.
Sauce: peel and finely chop the onions and sauté in butter until translucent. Roughly chop the mushrooms and add them, season with salt and pepper. Dust the fried mushrooms with flour and pour the broth over them. Add the cream and white wine, season with lemon juice. Pour the finished sauce over the carp and fry for about 15 minutes until golden brown.