To make the vinaigrette, place garlic, vinegar, oregano, sugar and chile flakes in a medium bowl along with a couple pinches of salt and a few turns of black pepper. Let sit for 5 minutes. Slow stream in olive oil while whisking to create an emulsified dressing. Season to taste with additional salt and pepper.
Preheat an oven to 400°F. Place bread on a rimmed baking sheet, then toss with olive oil, lemon zest salt and a few turns of pepper. Bake, tossing occasionally, until crispy and golden on the outside but still chewy in the center (about 8 to10 minutes). Let cool.
In a large bowl, mix the tomatoes, cucumber, roasted red peppers, onion, basil, and capers. Add the toasted bread and vinaigrette, tossing to combine. Season to taste with more salt and pepper. Enjoy immediately or let sit for 30 minutes before serving.