Put the almonds in a dry frying pan and fry over a medium heat. Shake regularly and watch very closely. Remove from the heat as soon as you can smell the almonds and they are just starting to take on some colour.
Repeat with the flaked almonds and reserve them for the garnish.
Cover the bread with the water and soak for 10 minutes until softened. Drain and squeeze out the water.
Put the whole almonds into a food processor or blender. Add the bread and process until the almonds are fairly finely ground. Add the garlic and cucumber and continue to blitz, then drizzle in the rest of the water, the olive oil and half the vinegar.
Taste. Season with salt and white pepper, then drizzle in a little more vinegar if you think it needs it. The soup should be very smooth – if it seems grainy, push it through a fine sieve.
Transfer to a bowl or jug, cover and chill for two hours.
To serve, ladle into bowls and top with the flaked almonds, peeled grapes and a drizzle of olive oil.