Bring a large pot of water to a boil and place beets inside. Cook, uncovered until tender – about 30 minutes. Then remove beets with a slotted spoon and set aside to let cool. Strain the beet cooking liquid through a fine sieve and set aside to let it cool.
In a large bowl, combine 1 ½ cups of the beet cooking liquid, the chicken stock, yogurt, lemon juice, sugar, salt, and pepper.
Peel skin from cooled beets and dice finely.
Then add the beets, cucumbers, scallions and dill into the soup mixture.
Cover and let chill for at least 6 hours, but overnight is preferable.