Wash the potatoes and boil them with skin in salted water for about 10 minutes. Beetroot also wash thoroughly and boil in salted water for about 25 minutes. Drain potatoes and beetroot, rinse with cold water and let cool down a little.
Cut both into slices. Peel and halve the onion and cut into slices. Wash parsley, dab dry and chop finely, except for something for the garnish. Mix vinegar and soy sauce with salt, pepper and parsley.
Beat sesame oil into it. Mix the potatoes, beetroot, onion slices and parsley vinaigrette in a bowl, cover and leave to stand for 15-30 minutes. In the meantime, wash the radish sprouts and drain well on a sieve.
Season potato salad with salt and pepper. Finally fold in the radish sprouts.