1. Place one tablespoon oil, soy sauce, and frozen garlic in a ziplock bag and marinate chicken in the mixture. You can do this up to two days in advance.
2. Place the pineapple in a bowl and add another tablespoon of oil, just enough to coat. Cut the shiitake mushrooms in half and toss them in the remaining tablespoon oil.
3. Use metal skewers or soak wooden ones in water for half an hour.
4. Thread the pieces of chicken on the skewers, alternating with the mushrooms and pineapple.
5. Preheat your grill to high. Place the skewers on the grill, cooking halfway through. Turn over and brush generously with white wine sauce. Just before you’re ready to take it off the barbecue, turn it back to the other side and brush the first side with the white wine sauce. Let sit for two minutes before serving.
When adding a marinade during grilling, it’s best to add it towards the end, so you can prevent the natural sugars in the marinade from burning.