1 In a medium sized bowl, combine canola oil, lemon juice, lemon zest, orange juice, oregano, salt, pepper and garlic.2 Whisk until ingredients are well combined.3 Add chicken, mushrooms, asparagus and tomatoes. Toss until well coated.4 Marinate for 20-30 minutes in the refrigerator.5 Thread chicken pieces and vegetables alternately on skewers. Discard marinade.6 Meanwhile, heat barbecue to medium heat. Grill skewers on lightly oiled grill, turning once with tongs.7 Grill until chicken cooked through, about 5-8 minutes.