Once the potatoes have cooled, peel them and cut them into cubes. Hard boil the eggs and cut into cubes. Also cut the cucumber, sausage and radishes (after cleaning) into cubes. Mix everything well in a bowl.
Then add the water and sour cream to the bowl and mix well again. Season to taste with the citric acid, salt, pepper and the chopped chives.
The soup tastes best after several hours in the refrigerator.