Bring a large pot of salted water to a boil. Stir the oyster sauce, fish sauce and vinegar in a small bowl; set aside.
Add the bok choy to the boiling water and cook until bright green and tender, about 1 minute. Drain well.
Rub the pork with the turmeric; season with salt and pepper. Heat 2 tablespoons vegetable oil in a large nonstick skillet over medium heat until very hot. Add the pork and cook until browned on the bottom, about 4 minutes. Flip, add the scallions to the skillet and cook until the pork is browned on the other side and the scallions are golden, about 4 more minutes. Transfer the pork and scallions to plates.
Heat the remaining 2 tablespoons vegetable oil in the skillet over high heat. Add the garlic and chile and cook until golden, about 30 seconds. Add the bok choy and oyster sauce mixture; cook, tossing, until slightly thickened, about 30 seconds. (If the sauce is too thin, remove the bok choy to the plates and continue cooking the sauce to thicken.) Serve with the pork chops.