Peel the cucumber, cut in half, scrape out the pips, chop the hollowed out bodies into 10ml slices and soak in a bowl of salted water for half an hour.
Slice the capsicum and remove any of the internal white flesh then place under the grill for around 5 minutes or long enough for the skin to be well scorched.
Remove from grill and wrap in foil for ten mins to make the capsicum sweat, then when you remove the skin it will come away easily and you won't burn your fingers.
For skin-free tomatoes, prick them all over with a knife and place in boiling water until the skin splits. Let them cool for a while then peel the skin away.
Cut tomatoes and scoop out the pips then place all prepared flesh of tomatoes, capsicums and drained cucumbers into a blender.
Finely chop garlic, oregano and onions to add to the blender.
Then remove bread crusts and cut into slices to add to the blender.
While all is blending nicely, measure out and add the olive oil and red wine vinegar.
Strain the mixture through a sieve ensuring you press out as much liquid as possible. You could also use a muslin bag to ladle the half dry remains into to squeeze out the last tasty drops (but this is a bit of an effort for only small gain).
Season to taste and stir in the water and ice cubes before serving with a garnish of slices of any of the ingredients - though cucumber floats well and really looks the part along with a few extra ice cubes.