Wash the cabbage leaves clean and spin them in a salad spinner to get them thoroughly dry.
Rip the cabbage leaves into 1½- to 2-inch pieces.
Heat your wok over high heat until it starts to smoke lightly. Add the oil and sear the pork (if using) for 1 to 2 minutes, until lightly brown around the edges.
Add the garlic, ginger, chilies (if using), and the white parts of the scallions. Reduce the heat to medium and stir-fry for 1 minute, taking care not to burn the garlic.
Increase the heat to high and add the cabbage. Stir-fry for 2 minutes, until the cabbage begins to wilt.
Add the oyster sauce, Shaoxing wine, light soy sauce, sugar, and white pepper. Mix well and cook for 1 to 2 minutes using high heat to cook off the liquid. (If you like the cabbage soft, cover and cook for 2 minutes.)
Stir in the black vinegar, the green parts of the scallions, and salt to taste.
Serve immediately.
