Cut the boiled eggs in half. Separate the whites from the yolks. Mash the yolks in a bowl with 1 tbsp. sour cream and horseradish. Season with salt. Dilute 200 ml of kvass. Stir. Cut potatoes (with or without jacket), cucumber, eggs and sausage into small cubes. Ring the radish. If it is big, cut it in half and then cut thin. Finely chop the onion and mash it in a mortar with a pinch of salt. Put the cut ingredients in plates and leave a few slices of radish for garnishing. Add a green onion. Ladle the spicy dressing and the remaining kvass. Add a spoonful of sour cream, garnish with radish and serve.