Cut the rice cakes into thin slices. If the cakes are too hard, soak in cold water for a few hours until soft. Mix the pork with cornflour, a little bit of water, Shaoxing wine, sugar, vinegar and salt in a bowl.
Heat the oil in a wok until hot. Stir fry the pork for about 2-3 minutes then remove and set aside. Add the rice cakes and enough water to cover them. Bring to the boil. Stir in the pickled mustard greens and pork. Cover the wok and cook over low heat for about 8 minutes. Transfer to a bowl and serve.
Glutinous rice cakes, pickled mustard greens and Shaoxing wine can be purchased in Asian speciality shops or online.
Pickled Mustard Greens
Pickled mustard greens are the pickling of any Asian green vegetable but typically a variety of bok choy.