Clean and wash the radishes. Peel and finely dice the shallots.
Heat the butter in a saucepan and add about 3/4 of the radishes and shallots and sauté over low heat. Add the vegetable stock and cook gently for about ten minutes.
Add the remaining radishes, cream cheese and sour cream and puree the soup. Heat again, but don`t let it boil anymore. Season the soup to taste. Rinse and dry the cress.
Divide the soup between two plates, sprinkle with cress and serve immediately. I fried a slice of ham and served it with it.