1. Mix the diced tomatoes, peppers and cucumber with the crushed garlic and olive oil in the bowl of a food processor or blender. Squeeze out the bread, tear it roughly into chunks, and add to the mixture.
2. Blend until smooth, then add the salt and vinegar to taste and stir well.
3. Pass the mixture through a fine sieve, then cover and refrigerate until well chilled.
4. Serve with garnishes of your choice: I liked diced black olives, hard-boiled egg and small pieces of cucumber and pepper; mint or parsley also works well, and many people add spring onion, cubes of Spanish ham and so on.