Usually panzanella calls for stale bread. If you don't have it, you can also bake it in the oven for 15 minutes like I did. Preheat your oven to 350 °F. Cut the ciabatta into cubes and place them on a baking tray lined with parchment paper. Bake for 15 minutes.
Roughly chop the tomatoes, cucumber, bell pepper, and the red onion. Place everything in a large bowl. Rinse the capers and add them to the vegetables.
Make the dressing. Combine all of the ingredients for the dressing in a small bowl and stir well.
Add the roasted ciabatta and the dressing and stir. Let it sit for about an hour before serving it. Tear the basil leaves and add them to the salad just before serving it.