Cut the beef and rub the pieces with the salt and vegetable oil. Prepare the sauce ingredients and chop the ginger.
Heat the wok and add oil. When oil is ready, add the beef, pushing the pieces out so that they cook evenly. Turn once. Stir-fry until the meat changes color. Remove from wok and set aside.
Add oil and stir-fry the ginger. Add the oyster sauce and sugar. Make a well in the middle of the wok and add the sauce mixture, stirring to thicken. Add the meat, mix quickly, and serve on a heated dish.