Prepare vegetables: skin tomatoes (if using for garnish) and set aside; seed peppers; peel cucumber portion; dice garnish vegetables and reserve chilled.
Soak bread 30 minutes in cold water; squeeze dry.
In a blender combine peppers, cucumber, garlic, coriander leaves, chilli, soaked bread, onion, vinegar, olive oil, and iced water; blend until roughly but uniformly chopped (retain some texture).
Season with salt and black pepper; chill well. Add a few ice cubes if serving immediately.
Fry diced bread for croutons in a little olive oil until golden (if using).
Serve soup cold with separate bowls of diced tomato, pepper, cucumber, and croutons for topping.