01 - In a blender, combine the cooked beets, buttermilk, yogurt, and lemon juice. Blend until smooth.
02 - Season the beet mixture with salt and pepper, then stir in the diced cucumber, sliced radishes, and chopped dill.
03 - Chill the soup in the refrigerator for at least 1 hour before serving.
04 - Serve cold, garnished with additional dill and a dollop of yogurt if desired.