Peel, wash and slice the carrot. Peel the onion and cut into wedges. Wash the fish and pat dry.
Bring the lemon juice of 1 lemon, 3/4 l water, onion, carrot and bay leaves to the boil, add pieces of salmon and let stand for 4 minutes.
Wash 1 lemon and cut into thin slices. Wash dill shake dry. Carefully lift the fish out of the stock and keep warm. Pour the brew through a sieve and collect it. Measure out 3/8 l fish stock.
Heat the butter in a saucepan, dust with flour, sweat and deglaze with fish stock while stirring. Add the cream and horseradish and bring to the boil. Refine with white wine and season with salt, pepper and sugar as required.
Arrange the fish with a little sauce on a platter. Garnish with lemon wedges and dill. Add the rest of the sauce.