Peel and grate the horseradish. Wash the chives, shake dry and cut into fine rolls. Puree the horseradish and chives, except for a little for garnishing, with vinegar, apple juice and crème fraîche.
Peel and wash the potatoes and cut them into sticks. Wash fish, dab dry and sprinkle with lemon juice. Season with salt and pepper. Heat 2 tablespoons of oil in a frying pan and fry the potato sticks in it while turning for 5-8 minutes.
In a second pan, heat 1 tablespoon of oil and fry the fish in it for about 3 minutes on each side. Mix the potatoes with 4 tablespoons of horseradish sauce. Arrange with the fish on plates. Garnish with horseradish and chives.
Add the rest of the sauce.