3 tablespoons good olive oil 1 pane turano, cut into 1-inch cubes (6 cups) 1 teaspoon kosher salt 2 large, ripe tomatoes, cut into 1-inch cubes 1 hothouse cucumber, unpeeled, seeded, and sliced 1/2-inch thick 1 red bell pepper, seeded and cut into 1-inch cubes 1 yellow bell pepper, seeded and cut into 1-inch cubes 1/2 red onion, cut in 1/2 and thinly sliced 20 large basil leaves, coarsely chopped 3 tablespoons capers, drained 1 teaspoon finely minced garlic 1/2 teaspoon Dijon mustard 3 tablespoons Champagne vinegar 1/2 cup good olive oil 1/2 teaspoon kosher salt 1/4 teaspoon freshly ground black pepper