Wash the potatoes and cook covered in boiling water for about 20 minutes. Wash and peel cucumbers and slice them into thin slices. Mix the cucumbers with 1/2 tsp. salt and put aside to allow them to infuse. Wash dill, shake dry and chop finely. Mix 4 tablespoons lemon juice, dill and approx. 1 tablespoon sugar. Drain potatoes, quench and peel. Let the potatoes cool down
Peel and finely chop the onion. Heat the fat in a pot and sauté half of the onions in it. Add 25 g flour and sauté briefly. Add stock and cream while stirring, bring to the boil and simmer at low heat for about 5 minutes. Stir mustard into the sauce and season to taste with salt, pepper, 1 tbsp. lemon juice and a little sugar
Wash the fish fillet, dab dry and cut into approx. 12 equal pieces. Sprinkle with salt. Put 40 g flour in a bowl, toss fish pieces in it, take them out and tap the flour a little bit. Drain the cucumbers and mix with the lemon-dill marinade in a bowl
Finely dice the bacon. Cut potatoes into slices. Heat 1 tablespoon of oil in a large frying pan, leave the bacon crisp in it and take it out. Put 2 tablespoons of oil into the hot pan, fry the potatoes for 8-10 minutes while turning them until crispy brown. 3 minutes before the end of the frying time, add the remaining onion cubes and fry. Finally, season with salt and pepper and fold in the bacon
Heat about 3 tablespoons of oil in a second large pan, fry the fish pieces for 3-4 minutes, turning them until golden brown, then place them on the finished fried potatoes. Heat mustard sauce and pour over the fish. Add cucumber salad