Whip cream until stiff, add horseradish and stir until smooth. Wash the dill, except for a few flags for garnishing, chop finely and stir into the cream. Season to taste with salt and pepper.
Spread the salmon slices with the horseradish cream, roll up and cut into 1 cm thick slices. Mix lemon juice with salt, pepper and sugar, add oil. Wash the cucumber, remove seeds, cut into small cubes and add to the vinaigrette.
Arrange salmon slices on a plate, drizzle with the vinaigrette and serve garnished with dill flags and parsley. Serve with fresh white bread with curly butter.