Cut the onion into fine cubes and sauté in the butter. Pour in the broth and add salt and pepper as required. Then add the whipped cream and let everything simmer for about 8 minutes.
Peel the cucumber and cut into fine cubes or grate and then add to the soup with the dill and bring to the boil again.
Optionally, the soup can then be made a little thicker with the hand blender.