For the sauce, wash the lemon thoroughly, grate dry, finely grate the peel and squeeze the juice. Grate the horseradish. Mix sour cream, lemon peel and juice, 2 tsp. horseradish and oil. Season to taste with salt, pepper and sugar
Clean and wash the radishes and cut them into thin slices. Wash the cucumber, cut off the ends, peel the cucumber in fine strips with a wide peeler. Clean, wash and cut spring onions into fine rings
Mix cucumber, radishes and spring onions. Line a plate with salmon slices, spread the cucumber mixture in the middle. Pour the sauce in a blob and sprinkle with poppy seeds