1. Prepare grill.
2. Brush chicken with 1 tablespoon vinaigrette. Place chicken, zucchini, and onion on a grill rack coated with cooking spray. Grill 3 to 4 minutes on each side or until chicken is done and vegetables are tender, adding tomato halves to grill rack after 2 minutes. Cook tomato 2 minutes on each side. Remove chicken and vegetables from grill. Cut chicken crosswise into thin slices; coarsely chop vegetables.
3. Combine chicken, vegetables, and remaining 6 tablespoons vinaigrette in a large bowl, tossing to coat. Add arugula and cheese; toss gently.
Serve with: Grilled Garlic Bread
Serve now of later This salad is delicious served immediately, but leftovers make an equally tasty chilled lunch-to-go. Just be sure to pack the vegetable and chicken mixture, salad greens, and salad dressing in separate containers, and toss them together right before serving.