Clean the trout of viscera and wash them, salt them and put them in a shallow pan. Add 2/3 cup (150 ml) cold water over the top and cook on medium stove about 5 minutes. Remove the fish and carefully remove their skin and separate them into dishes.
Strain the water and return it to the stove. Add the broken cream, dissolved mustard mixture and allow to boil. Add the flour.
Once the sauce boils, remove from the heat, season with salt and pepper and sprinkle with chopped parsley. This sauce is poured over the fish.