Preheat large saute pan on medium. Add 2 tablespoons of olive oil and heat for 45 seconds. Add cubed bread, salt, pepper. Stir often until golden, about 5 to 10 minutes; allow to cool slightly.
While the bread is cooking, whisk together 1/4 cup of olive oil and balsamic vinegar. Gently toss together the bread, tomatoes, onion, basil, garlic, and mozzarella cheese. Toss with the vinaigrette and let stand for 20 minutes before serving.