Cut the cabbage into 8 equal wedges, and then cut each wedge into equal triangular pieces. Set aside.
Combine the soy sauce, sugar, and 2 tablespoons water to form a sauce. Set aside.
Combine the cornstarch and the other 2 tablespoons water; Set aside.
Heat the oil in a wok over high heat until hazy. Add the cabbage and stir-fry for two minutes. Stir in the sauce and continue to stir-fry for another two minutes or until only half of the liquid remains. Slowly add the cornstarch mixture until the mixture thickens.