Wash the grapes and remove the stalks. Process them in the blender.
Put the grape juice in the blender. Peel the cucumber, halve it lengthwise
and remove the seeds. Cut the cucumber into thick slices and add these
slices to the grape juice in the blender. Add the shallot, the garlic, the salt
and the pepper and run the machine briefly. Pour the mixture into a
bowl and stir the yoghurt and Tabasco through it.
Chill the soup by putting it in a covered bowl in the refrigerator for
30 minutes. Serve in large soup bowls and garnish with cucumber slices
and halved grapes.