Slice the beef thinly and marinate in a mixture of sugar, corn flour, soya sauce, sesame oil and rice wine. Set aside for 15 minutes.
Blanch the kai lan in boiling water until the stalks are slightly tender and set aside. Reserve 3 tablespoons (45ml) of the mushroom liquid then drain the mushrooms. Remove stems and slice mushrooms.
Heat a little oil in pan and saute the sliced garlic until lightly brown. Add the mushrooms and kailan and stir fry for 2 minutes.
Add the beef and stir fry for 2 minutes. Mix the reserved mushroom liquid with a teaspoon of corn flour. Pour in this mixture into the pan and add oyster sauce. Mix everything together and simmer until the sauce thickens.