Wash the meat, dab dry and season with salt and pepper. Heat oil and fry fillets on each side at medium heat for about 5 minutes. Cook lentils in boiling water for about 10 minutes.
Clean and wash the spring onions, put 2 spring onion ends aside for garnishing. Cut the rest into rings. Clean and clean the mushrooms, cut into slices. Take out meat, put aside. Drain the lentils, let them drain.
Sauté the mushrooms in the hot frying fat. Add spring onions and rosemary and fry briefly. Add 350 ml water, bring to the boil and stir in the stock. Season with salt and pepper. Remove from heat and stir in vinegar, mix lentils with marinade, season with salt and pepper.
Wash and clean the salad and drain well. Mix with the lentil salad. Cut the meat into slices and arrange on the salad. Sprinkle with parmesan. Garnish with set aside spring onions and serve immediately.