Cut the chicken into 1-inch pieces. Mix the seasoning ingredients together and mix with the chicken. Leave to marinate for 15 minutes.
Place a plate in a steamer and put the chicken, mushrooms, ginger, half the onion and the stock on top. Steam over boiling water for 15-20 minutes.
Serve with the remaining onions sprinkled over the chicked, The steaming can also be done on a greased lotus leaf or a banana leaf. The flavor is quite stunning.
If you can obtain dried mushrooms do use them as their flavor is far superior to ordinary mushrooms.