Wash the potatoes and boil in water for about 20 minutes. In the meantime clean and wash spring onions and radishes. Cut spring onions into rings, radishes into fine slices. Mix quark, sour cream, wasabi (! carefully!) and prepared ingredients.
Season to taste with salt, pepper and lemon juice. Peel the potatoes. Serve in portions with quark and Bündnerfleisch.