Chilled Russian Borscht

In a large pot, cover the quartered beets with the water and bring to a boil. Simmer over moderately low heat until the beets are tender when pierced with a fork, about 30 minutes. Using a slotted spoon, transfer the beets to a plate. Coarsely shred the beets in a food processor. Return them to the pot and add the sugar, lemon juice and cider vinegar; season with salt and pepper. Refrigerate the soup until chilled, for at least 4 hours or preferably overnight. Meanwhile, bring a small saucepan of salted water to a boil. Add the potato cubes and cook until tender, about 7 minutes. Drain and cool under cold water. Pat dry and transfer to a medium bowl. Add the cucumbers, radishes, scallions, eggs, dill and parsley. Ladle the chilled borscht into bowls. Garnish with the vegetable and chopped egg mixture, top with a generous dollop of sour cream and serve.