Squeeze out the excess water from the soaked mushrooms and bamboo shoots. Discard the stems of the mushrooms. Cut the bamboo shoots into smaller pieces.
Heat a wok with oil until hot. Fry the chicken for a few minutes then drain. Set aside. Discard all but 2 tablespoons oil.
Heat the wok again until the oil is hot. Stir fry the ginger and white parts of the spring onion until fragrant. Stir in the chicken, mushrooms, soy sauce and oyster sauce.
Add the rice wine, sugar, bamboo shoots and stir fry. Add a little bit of water and continue to cook until the chicken is cooked through.
Transfer all the contents of the wok into the large saucepan with the spinach. Cook over a medium heat for a few minutes.
Dissolve the cornflour and salt with a little bit of water and add into the wok. Cook until slightly thickened then season with the white pepper and garnish with the green parts of the spring onion. Serve.
Dried shiitake mushrooms, rice wine and dried bamboo shoots can be purchased in Asian speciality shops or online.