Preheat oven to 350°.
Combine first 5 ingredients in a bowl; stir with a whisk. Add tomato, onion, basil, and bacon; toss well. Set aside.
Arrange bread cubes in a single layer on a baking sheet; lightly coat bread with cooking spray. Bake at 350° for 15 minutes or until toasted; cool. Add bread and lettuce to tomato mixture; toss gently to combine. Serve immediately.