1. Heat grill.
2. In 8 inch baking dish, mix zucchini, bell pepper and onion.
3. Drizzle with oil, toss to coat.
4. With tongs, place veggies in grill basket.
5. Place grill basket over medium heat, cover grill.
6. Cook 15 to 20 minutes, stirring occasionally.
7. Remove from grill and place veggies in 8 inch dish.
8. Stir in oregano and garlic.
9. Cut 18x18 inch sheet heavy duty foil, lightly spray with cooking spray.
10. Cut loaf in half lengthwise.
11. Spread cut sides of bread with dressing.
12. Top bottom half with grilled veggies.
13. Place cheese slices diagonally over veggies, overlapping slightly.
14. Cover with top half of bread.
15. Place on foil, wrap securely using double fold seals, allowing room for heat expansion.
16. Reduce grill to low heat.
17. Place wrapped loaf on grill and cook 7 to 10 minutes or until warm.
18. Carefully unwrap loaf to allow steam to escape.
19. Cut loaf into 4 sandwiches.