Wash the potatoes and boil in boiling water for about 25 minutes until soft. Wash the cucumber and cut or slice it. Wash the dill, shake dry and chop the flags finely, except for one stalk
Peel and finely chop the onion. Drain the potatoes, rinse briefly in cold water and peel. Cut potatoes into slices and put them into a bowl together with the cucumber slices. Simmer vinegar, half of the onion cubes and 200 ml broth in a small pot for about 2 minutes, then pour over the potatoes. Season the salad with salt and pepper and let it stand for about 20 minutes
Heat 1 tsp. oil in a frying pan. Fry half of the onion cubes in it until transparent. Add the mustard and stir in 1 tbsp. flour. Slowly add 100 ml broth and milk while stirring. Season sauce with salt, pepper and a little sugar and simmer for about 5 minutes
Wash the fish, dab dry and season with salt, pepper and a little lemon juice. Turn the fish fillets in approx. 2 tbsp. flour, knock off excess flour. Heat 1 tablespoon of oil in a coated pan. Fry the fish for approx. 4 minutes while turning.
Bring the sauce to the boil again. Arrange fish, potato salad and sauce, garnish with lemon and dill
Waiting time approx. 10 minutes