Stir the fried potatoes into 1/2 litre of boiling water and let it boil for about 8 minutes in an open pot until the water is absorbed by the potatoes. Meanwhile wash the fish, dab dry and cut into pieces.
Heat the oil in a pan and fry the fish in it for 3-4 minutes on each side. Season with salt and pepper. Clean, wash and chop the spring onions. Cut cucumbers into half slices.
Remove fish from the pan and keep warm. Add the fried potatoes to the frying fat and fry all around for about 10 minutes until golden brown. Approx. 5 minutes before the end of the frying time add spring onions and gherkins and fry with them.
Add the fish and warm it up again. For the sauce, stir the sauce powder into 1/4 litre of lukewarm water with a whisk and bring to the boil. Season to taste with mustard and sugar. Chop dill finely and stir in.
Arrange the fried potatoes together with the sauce on plates and serve garnished as desired with dill flags and flowers.