Wash the radish leaves, drain and chop, put aside enough to garnish beforehand, cut them into fine strips.
Dice the potatoes and onion and sauté in half the butter. Deglaze with the broth and cream and simmer for 15 minutes. Add chopped radish leaves and puree. Season to taste with salt, pepper and nutmeg and place in preheated soup plates. Fry the prawns in the remaining butter for 2-3 minutes and add them to the soup with the radish leaf strips.