In a small mixing bowl add: chicken stock, dark soy sauce, Chinese cooking wine, oyster sauce, sugar and cornstarch mixed with water. Mix together and set aside for later use.
Heat a wok or pan on a medium to high heat and a tablespoon of oil. Pour the spring onions into the wok and stir fry for 30 seconds.
Add the diced chicken and continue to stir fry for a further 2 minutes or until the chicken is cooked on the outside.
Pour the mushrooms into the wok and stir fry for a further two minutes. Then add the sliced garlic and ginger and stir until evenly distributed.
Add the pre-mixed sauce to the wok, stir and leave to simmer for 10 minutes or until thickened. Stir occasionally to coat the chicken and mushrooms whilst the sauce is thickening.