Peel and finely dice shallots. Heat the butter and fry the shallot cubes in it until translucent. Pour in white wine and let it boil down a little. Pour in the fish stock, 100 ml of water and cream. Let everything simmer over high heat for about 10 minutes. Stir lobster paste into the soup and simmer for another 5 to 10 minutes while stirring.
Wash the parsley and chop it very finely. Mix the cream cheese, horseradish and parsley together. Brush the salmon slices with the cream cheese and roll up. Cut the rolls into thin slices.
Wash tarragon and shake dry. Pluck and add to the soup. Season with salt and pepper. Add salmon rolls and serve immediately.