In the jar of a blender, combine 2 cucumbers, 1 clove garlic, and 1/2 cup stock. Blend until smooth. Transfer to a large bowl. Blend the remaining 2 cucumbers, clove of garlic, and 1/2 cup stock until smooth; add to bowl.
Whisk in the remaining 2 cups stock and the sour cream, salt, and lemon juice. Cover, and chill in refrigerator for at least 1 hour and up to 4 hours. Place tomatoes, parsley, scallions, walnuts, eggs, and cheese in separate bowls. Ladle soup into bowls, and garnish with desired condiments.