Wash potatoes and beetroot thoroughly and cook separately in plenty of salted water for about 15 minutes. Wash and clean spring onions and cut into thin strips. Put the spring onions in ice water so that they roll up
Mix sour cream and vinegar. Season with salt and pepper. Drain potatoes, rinse, peel and dice coarsely. Rinse beetroot with cold water, peel and cut into fine slices
Wash, clean and quarter radishes thoroughly. Mix the potatoes, beetroot, spring onions and radishes with the dressing. Arrange in bowls. Sprinkle with cress