Clean the mushrooms, wash and halve them. Peel and finely chop the onion. Wash the meat, dab dry, halve if necessary. Season with salt and pepper. Wash the thyme, shake dry and chop the leaves coarsely
Heat 2 tablespoons of oil in a large coated frying pan. Fry the meat for about 2 minutes, turning it over, remove it and put it into an ovenproof dish. Fry the mushrooms in the oil for about 5 minutes, then add the onions and fry for another 1-2 minutes
Take out and add to the pork tenderloin. First dust the roasting tin with flour, then deglaze with cream while stirring. Add thyme and cook the meat loosely. Season with salt and pepper and pour over the pork tenderloin. Cook the pork tenderloin in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 20 minutes
Peel, wash and grate potatoes and carrots. Mix potatoes, carrots, egg yolk and starch and season with salt, pepper and nutmeg. Heat 1-2 tablespoons of oil in a coated frying pan. Fry about 16 small Rösti in portions, turning them over for 5-7 minutes.