Trim the kohlrabi greens and set aside. Remove the peel from the kohlrabi, potatoes and onions and cut into cubes.
Sauté the diced vegetables in light butter or butter on 2 or automatic heat 8 to 9, add the clear soup and cook the vegetables for 1 5 minutes on 1 or automatic heat 5 to 6 with the lid closed.
In the meantime, cut the salmon into thin strips.
Blend the soup with the hand blender. Add half to the fresh cream, bring to a boil and season with salt, pepper and nutmeg.
Fill the soup into plates. Spread the remaining crème fraîche, the salmon and a little bit of kohlrabi greens evenly on top and bring to the table.