If you don’t already have stale bread and are using fresh bread, tear it into chunks and spread out on a tray. Leave to stale for a minimum of 3 hours.
Put the tomatoes in a colander set over a bowl. Sprinkle the tomatoes evenly with the teaspoon of salt and leave to drain for 30 minutes.
Meanwhile, put the cucumber, red onion, olives and bread in a large salad bowl. If are not keen on raw onion, soak the red onion in cold water while you wait for the tomatoes to drain.
Gently press the tomatoes with your hands to squeeze out more juice, but not so hard as to squish them. Add the tomato flesh to the salad bowl.
Add the capers, garlic, sugar and red wine vinegar to the tomato juices. Blend using an immersion (stick) blender or, if you don’t have one, a normal blender. Just use a whisk if you don’t have either.
Slowly drizzle 4 tbsp of the olive oil, while blending, into the dressing. Pour enough dressing onto the salad to soak all the bread pieces (this might be all of it, depending on how much juice you get from your tomatoes). Toss gently so the dressing coats everything.
Leave for 15 minutes for the bread to soak up the dressing. Don’t skip this step!
Drizzle over the remaining 1 tbsp olive oil, season with salt and pepper, sprinkle the basil on top and serve.