Heat 3 tablespoons olive oil over medium heat. Add the bread cubes and toss to coat. Saute until golden brown and crispy, 5 - 7 minutes. Toss with 1 teaspoon salt.
Combine tomatoes, cucumber, peppers, onion, parsley and capers in a medium mixing bowl.
Whisk together the garlic, dijon, vinegar, remaining 1/4 cup olive oil in a small mixing bowl and pour over vegetables.
Add toasted breadcrumbs and toss to combine. Season with salt and pepper.