1Cut bread into 2-inch pieces. In 10-inch skillet, heat 3 tablespoons oil over medium-high heat. Add bread cubes; cook, stirring frequently, until browned. If needed, add more oil. Remove bread from skillet; set aside.
2In small bowl, beat vinaigrette ingredients with whisk until blended. Add 1/2 cup oil in slow, steady stream, beating until well blended. Add salt and pepper to taste; set aside.
3Remove seeds and cut bell peppers into 2-inch pieces. Peel and cut cucumber horizontally in half; remove seeds and cut into 2-inch pieces. Cut cherry tomatoes in half.
4In large bowl, combine vegetables and basil. Add vinaigrette; toss. Add croutons; toss again.