Combine vegetable oil, lemon juice, soy sauce, garlic, oregano, salt, and pepper in a large resealable bag.
Place chicken in bag, making sure all pieces are covered.
Seal bag and place in fridge and let marinate for at least 4 hours (or overnight).
On metal or soaked wooden skewers, thread chicken, onion, pepper and pineapple.
Discard remaining marinade in bag.
Heat grill to medium heat.
Place skewers on grill and cook for 7-8 minutes per side or until chicken is no longer pink in the middle (if using a meat thermometer, make sure it registers 165 degrees F).
Remove from grill and serve.
Notes
We like to serve this over some rice with teriyaki sauce.