Finely grind bread in the universal chopper. For the remoulade, clean, wash and finely dice the radishes. Wash the cucumber and dice very finely. Peel and finely dice the onion. Wash dill, shake dry, pluck flags from stalk and chop finely.
Mix sour cream, 100 g buttermilk and salad cream. Season with salt and pepper. Mix the radish, onion and cucumber and, except for 1 tbsp. for garnishing, stir into the cream. Stir dill, except for 1 tbsp. for garnishing, into the cream and leave to stand.
Peel and wash the potatoes and cook them in boiling salted water for about 25 minutes. Wash fish, dab dry and cut into 4 pieces. Season with salt and pepper. Turn fish first in condensed milk, then in toast crumbs. Heat the oil in a pan and fry the fish for 2-3 minutes on each side at medium heat.
In the meantime heat 250 g buttermilk while stirring. Remove from the stove. Drain the potatoes and let them steam a little. Add hot buttermilk and mash coarsely with a potato masher. Season to taste with salt and nutmeg.
Potato mash sprinkled with dill, arrange 1 piece of fish and some tartar sauce on plates, sprinkle with radish mix. Add the rest of the tartar sauce.