Heat combined oils in a wok or heavy-based frying pan on high. Stir-fry chicken in batches for 3-5 minutes, until browned. Set aside and keep warm.
Add garlic and ginger to same pan and stir-fry for 1 minute. Add mushrooms and stir-fry for another 3 minutes, until juices are absorbed. Cut buk choy in half lengthways and stir-fry until wilted. Return chicken to pan and cook for 1-2 minutes.
Combine chicken stock, rice wine, soy sauce and cornflour in a small bowl. Add to chicken and vegetables and cook for 1 minute, until vegetables are glazed. Serve with rice.