1. melt the light butter or possibly butter in a saucepan and roast in it the onion, leek and fennel at medium temperature for 5-8 min until soft, stirring occasionally. Fold in the flour and roast over low heat for 3 min, stirring occasionally.
2. Add fish stock and potatoes, season with salt and pepper and make soup. Turn down the heat and simmer the potatoes for about 20 minutes with the lid closed.
3. simmer with the salmon for another 3-5 min until it is cooked and falling apart.
Stir in milk, whipped cream and dill and heat through (do not make).
Taste the soup before serving.