Wash the cucumber, cut off 1 cucumber slice and put aside. Peel the rest of the cucumber, cut it into large pieces and put it into the cup of a blender. Add buttermilk. Wash herbs, shake dry and chop finely.
Add to buttermilk, mix finely and season with salt, pepper and sugar. Wash and clean the tomato and cut into fine cubes. Pour the soup into a glass, add the tomato cubes and garnish with the cucumber slice and a bouquet of herbs.