Peel, wash and roughly grate the potatoes and carrots. Peel and finely grate the onion. Season with salt and pepper. Heat 3 tablespoons of oil in a pan. Add the toasted dough and press down a little.
Fry at low heat for 15-20 minutes. After about half the cooking time, slide on a lid and turn. In the meantime, wash the meat and pat dry. Heat 1 tablespoon of oil in a pan and fry the fillets for about 5 minutes, turning them over.
Place in an ovenproof dish and cook in a preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 10 minutes. Take out, pour Sauce Hollandaise over it and heat up again for about 2 minutes, cut open.
Cut the Rösti into pieces and arrange the chicken filet on plates. Sprinkle with parsley and garnish. Serve with salad.