Cook the lentils in about 1/2 l boiling water for about 10 minutes. Clean and wash spring onions and cut into rings. Clean mushrooms, wash if necessary and cut into slices. Slice the parmesan into shavings.
Wash the meat and dab dry. Heat 1 tsp. oil in a coated pan. Fry the meat for 5-6 minutes on each side. Season with salt and pepper. Take out.
Sauté the mushrooms in the hot frying fat. Fry the spring onions briefly. Deglaze with 100 ml water and vinegar, bring to the boil briefly. Stir in stock. Drain lentils, stir in. Season to taste with salt and pepper.
Clean, wash and drain the lamb's lettuce. Lift under the lentils. Cut the chicken into slices and arrange on top. Sprinkle with parmesan. Serve lukewarm or cold.