Clean and wash the leek and cut into rings. Peel the potatoes and then dice them. Steam both in the hot margarine in a saucepan and season with salt, pepper and nutmeg. Top up the broth, bring to the boil and simmer for about 20 minutes.
Wash the salmon fillet, pat dry and cut into thin slices. Particularly thin slices can be achieved by briefly freezing the salmon fillet or cutting frozen salmon fillet that has not been thawed.
At the end of the 20 minutes` cooking time, remove a third of the vegetables with the slotted spoon and set aside. Add the condensed milk to the soup and finely chop everything with a hand blender. Now add the salmon, the finely chopped dill and the remaining vegetables to the mashed soup, let it steep for about three minutes and season with salt, pepper and squeezed lemon juice.