For the duchess potatoes, boil 350 ml water. Remove the pot from the heat, pour in the milk, stir in the puree powder. Season to taste with salt, pepper and nutmeg and let it cool down a bit.
Wash the meat, dab dry. Rub with 1 teaspoon of oil, salt and pepper, place on the fat pan and bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for approx. 40 minutes. In the meantime, cook the eggs in plenty of boiling water for about 10 minutes, then let them cool down in cold water.
For the sauce, peel and halve the eggs, remove the yolks and pass through a sieve. Beat with vinegar, salt, pepper and sugar until foamy. Stir in the remaining oil drop by drop. Wash the herbs, dab dry and chop.
Put 2 tablespoons of herbs aside. Stir the remaining herbs and yoghurt into the sauce. Dice egg white and fold in. For the crust, mix cheese, sour cream and remaining herbs (leave some to sprinkle on the sauce if you like).
Spread on the fillet 10 minutes before the end of cooking time. For the vegetables, clean and wash the cauliflower and broccoli and cut into florets. Heat 1/4 litre of water. Add the vegetables and season with salt and pepper.
Cover and stew for about 10 minutes. Stir the egg yolk into the potato mixture, fill into a piping bag with a star-shaped spout and spray approx. 16 duchess potatoes onto a baking tray lined with baking paper.
Take the fillet out of the oven and keep it warm. In the meantime, bake the duchess potatoes for about 15 minutes at the same temperature. Heat the fat in a pan. Brown the flaked almonds in it. Toss the drained vegetables in it.
Cut the fillet into slices and arrange on a plate with the vegetables. Serve the sauce sprinkled with the remaining herbs with the duchess potatoes extra.