Combine first 5 ingredients in a small bowl; stir well, and set aside.
Combine zucchini and next 7 ingredients (zucchini through onion) in a medium bowl; toss gently. Spoon vegetable mixture onto a broiler pan coated with cooking spray. Broil 10 minutes or until tender and lightly browned, stirring occasionally.
Divide vegetable mixture evenly between pita halves. Drizzle 2 tablespoons dressing over each sandwich.