Trim crust from bread and soak in water.
Peel onion and garlic and finely dice.
Step 3, 4 and 5:
On the bottom of each tomato, score skin and place into a bowl of boiling water. Remove and place into an ice bath. Peel skin off tomatoes and cut in half. Remove seeds and stem.
Peel cucumber, cut in half lengthwise and remove seeds.
Rinse and trim peppers.
For the cucumber, peppers and tomatoes, cut 1/4 of each into small cubes and set aside for garnish.
Cut remaining vegetables into large pieces.
Place vegetable pieces into a kitchen blender and puree. Add white bread, onion and garlic to vegetable puree. Add 250 ml (approximately 1 cup) of cold water while blending to reach desired consistency.
Add vinegar and olive oil while blending and season with salt and cayenne pepper to taste.
Cover and refrigerate soup at least 30 minutes before serving. Ladle into bowls and garnish with small diced vegetables.
Add croutons, if desired, and serve.