Place the bread in a dish which will hold it in a single layer, and pour the milk over.
Leave until the milk has been absorbed.
Transfer the soaked bread to a blender and add the toasted almonds, peeled grapes, garlic, sherry vinegar, oil, half the water and a little salt.
Process until smooth.
Check the consistency and add more water until you get a soup-like consistency.
Adjust the seasoning.
Chill the soup until very cold, leave overnight.
Mix through some crushed ice.
Serve the soup in individually chilled bowls, garnished with some finely sliced and peeled grapes, a sprinkle of shaved almonds topped with a Dublin Bay prawn, a sprig of dill and two croûtons on the side.
The 2-day-old bread can be left out, however the bread acts as a thickening and emulsifying ingredient and allows the ajo blanco to hold its consistency.