Cover baking sheet with heavy-duty aluminum foil; coat with cooking spray. Arrange bell peppers, onion, zucchini, and tomato on baking sheet; coat vegetables with cooking spray. Broil 3 inches from heat 16 minutes, stirring once. Remove vegetables from baking sheet, and transfer to a large serving bowl.
Combine chipotle pepper and remaining 3 ingredients in a small bowl; stir with a whisk until blended. Pour over warm vegetables; toss gently to coat. Serve warm or chilled.