Wash the redfish fillets, dab dry and sprinkle with lemon juice. Peel onion and cut into cubes. Clean and chop the mushrooms finely. Wash parsley, dill and chives.
Chop the herbs or cut into fine rolls. Heat the fat in a pan and fry the onions in it until translucent. Add the mushrooms, season with salt and pepper and braise until the mushrooms no longer draw any liquid.
Let it cool down a little. Add the egg yolks and chopped herbs, except for a tablespoon, to the mushrooms. Place the fish fillets side by side in an ovenproof dish and spread the mushrooms on top. Bake in a preheated oven (electric: 200 °C/ gas: level 3) for approx. 12 minutes.
Meanwhile cook the ribbon noodles in plenty of boiling salted water for 8-10 minutes. Drain the noodles. Heat garlic butter in a pot and toss the noodles in it. Arrange fish and noodles on plates.
Sprinkle fish fillets with remaining herbs, garnish with lemon slice and parsley.