Hard boil eggs in boiling water for about 10 minutes, quench cold and let them cool down. Cut ham into strips. Clean, wash and slice the mushrooms. Clean, wash and drain the salad. Peel eggs and cut into slices. Stir mayonnaise, yoghurt and mustard until smooth.
Season with salt, pepper, sugar and lemon juice. Chop capers coarsely and fold in. Wash the chives, dab dry and cut into rings. Arrange the salad ingredients on plates. Spread the sauce on top and sprinkle with chives. Garnish with parsley as desired.