1.Peel and cut onion in half, then cut each half into 12 wedges. Cut each wedge in half, crossways, to get 24 wedges.
2.Thread pork, mushrooms and onion, alternately, onto 16 bamboo skewers. Place skewers in a shallow dish; brush to coat with marinade.
3.Spray kebabs with oil; cook on heated oiled grill plate (or grill or barbecue) until cooked.
Remember that when you put food onto skewers, not to squash everything together. Leave a little space between each item to allow the heat to circulate and to ensure everything cooks through. If you have time, soak bamboo skewers in water for 30 minutes to stop them from burning during cooking, or cover the ends in foil.