What will be needed:
~10 oz. of fish (hake, cod etc. for a more luxurious soup 50/50 of that and salmon)
1 root of parsley
1 small root of celery (1 slice of about an inch from a big one)
1 tablespoon of butter
2 tablespoons of flour
4.5 cups of fish stock
1/2 teaspoon of curry powder
1/4 teaspoon od cayenne powder
2 egg yolks
1/2 cup cream
Note: the root vegetables can be replaced with other stuff. Leek, onions, bell peppers etc.
To make the soup:
Dice the fish into small bit size cubes, dice the vegetables. Start heating the fish stock, when it is close to boiling melt the butter in a separate pan that is big enough to hold at least half of the fish stock. Once the butter is melted carefully mix in the flour stirring constantly. Once it has made a thick goopy paste ladle in the fish stock a little at a time. This will ensure a lump free soup.
Once all the fish stock and butter-and-flour-goop have mixed into one pour it back into the other (or what happens to be the biggest pan) put it aside.
Take the lemon juice of the 1/2 lemon and mix with the curry powder, cayenne powder, egg yolks and cream. Once mixed stirr it into the fish-stock (want a richer soup, add one more egg yolk and more cream)
Add the vegetables, bring it to the boil and let it bubble away for 15 minutes before adding the fish. Leave bubbling until the fish is done, which is about 5 minutes. Add salt to taste.
Garnish with a dollop of sour cream and a slice of leamon, serve with fresh bread and proper butter.