Wash the potatoes and cook in boiling salted water for about 20 minutes. In the meantime drain beetroot well. Cut fish into slices as desired. Clean and wash spring onions and cut them into small pieces.
Peel and slice the potatoes. Season vinegar with salt, pepper and sugar, bring to the boil. Add spring onions and oil. Pour hot over the potatoes. Wash apples, cut into quarters, remove seeds.
Cut the fruit flesh into slices. Sprinkle with lemon juice. Clean and wash the salad and pluck into bite-sized pieces. Line a plate with it. Mix the rest of the prepared ingredients and arrange on top.
For the sauce, wash and chop the dill. Stir in the sour cream. Season to taste with salt and pepper. Serve with the salad.