Dab the fillet dry, quarter it lengthwise and cut it into approx. 1⁄2 cm thick strips. Dice bacon finely. Clean and wash spring onions. Cut the white and green separately into diagonal rings. Clean the chanterelles, brush or possibly wash them.
Wash and chop the thyme.
Peel, wash and roughly grate the potatoes. Mix with egg yolk and 1 tbsp. flour. Season with salt and nutmeg.
Heat 2 tablespoons of oil in a large coated frying pan. Add approx. 4 tbsp. potato mixture per Rösti, spread flat and fry until crispy on both sides. Remove and keep warm.
In the meantime, heat 2 tablespoons of oil in a frying pan or a very large frying pan. Brown the meat in it in 2 portions. Take out. Fry bacon in hot frying fat until crispy. Fry mushrooms and white spring onion rings for 1-2 minutes.
Add butter, melt. One go. Dust with flour and sweat. Wine, 1⁄4 l Stir in water, stock and cream. Bring to the boil, add thyme. Simmer sauce for about 5 minutes.
Heat the fillet in the sauce. Season to taste and serve with the Rösti. Sprinkle with spring onion green. Serve with green salad.