Hardball the eggs and cook the potatoes until cooked, but not overcooked and soft, peel and cut into small cubes. Cool the eggs and if possible slice thinly. If the egg falls apart, then cube it and tell your family that's how it was meant to be made!
Cut the ham, cucumber, radishes into the smallest cubes you can.
Slice the green onions and dill and set aside for when you are garnishing.
Place eggs, potatoes, ham, cucumber, radishes and salt in a large pot (or individual bowls). Add the chilled Kvass and stir together.
It's best if your refrigerate for an hour to allow the soup to get really cold, before serving with the sour cream, dill and green onions. If you don't have time to chill, then you can serve with a few ice cubes. When mixing the sour cream, stir quickly so it doesn't curdle.