Panzanella with Cherry Tomatoes (Italian Bread and Tomato Salad)

Ingredients

• 1 1-pound loaf of country or other rustic white bread
• ⅓ cup olive oil
• Kosher salt ((to taste))
• ½ cup extra-virgin olive oil
• 3 tablespoons red wine vinegar
• 3 tablespoons balsamic vinegar
• ¼ cup minced shallots
• ½ teaspoon finely minced garlic
• Kosher salt and freshly ground black pepper ((to taste))
• 1 cup halved and very thinly sliced red onion
• 3 pints cherry or grape tomatoes ((halved or quartered if large))
• 5 baby or Persian cucumbers ((halved and sliced 1/2-inch thick))
• ¼ cup chopped or thinly sliced fresh basil