1. In a medium-size bowl, whisk oil, garlic, lemon juice, lemon zest, oregano, mint, salt and pepper. Pour into a large resealable plastic bag.
2. Add swordfish, tomatoes, zucchini and green pepper to bag, seal and shake, making sure all pieces are coated. Marinate in the refrigerator for 30 minutes, shaking bag once.
3. Heat gas grill to medium-high or prepare charcoal grill with medium-hot coals. Lightly coat grill rack with oil or nonstick cooking spray.
4. Thread kabobs with fish, tomatoes, zucchini and pepper, reserving marinade. Grill kabobs, covered, for 5 minutes, basting with reserved marinade once or twice. Turn and grill for another 5 minutes, basting once. Remove from grill and serve warm or at room temperature.