Wash the potatoes and cook in boiling salted water for about 20 minutes. Then rinse with cold water, peel and leave to rest for a while. In the meantime, boil eggs hard. Afterwards also rinse cold, peel and cut into slices. Peel, quarter and finely dice the onion. Cut cucumber and ham into small cubes. Cut potatoes into slices.
Bring the stock and onions to a boil briefly, pour over the slices and allow to draw. Pluck salad leaves from the stem. Line a suitable plate with about 5 pieces. Cut remaining leaves into fine strips. Mix mustard cream, yoghurt and cucumber water. Add salt and pepper to taste. Carefully mix the prepared salad ingredients and cream and arrange on the salad leaves