How to make
Place the finely chopped ginger root, onion and cayenne pepper in a pot. Arrange the fillets inside, pour 1 4/5 cups (450 ml) of water and bring to a boil. After 5 minutes, remove from the heat and leave the fish in the water for 5 minutes.
Transfer the fillets to a serving plate, cover and keep it warm. Boil the water from the fish. Boil on high heat for 5-10 minutes until the liquid is reduced, thickened and starts to look like a syrup. Add the vinegar.
Add the cream slowly and bring to a boil, then pour the mixture into a blender. Make a smooth sauce and pour into a clean pot. Mix the flour with 1 tablespoon water and add it to the sauce, stirring constantly. Add the spices.
Boil for 1 minute, then pour over the fillets. Garnish with dill and lemon as desired.