Put the pork, hoisin and soy sauce in a bowl and allow to stand for 10 mins. Heat the grill to high, shake off any excess sauce, then lay the pork on a tray. Grill for 5 mins, turning halfway, until cooked through. Remove and leave to rest in a warm place for 5 mins.
Heat the oil in a wok, add the ginger, and stir-fry for 1 min. Add the bok choi, then stir-fry for a further 2 mins. Tip in a dash of soy sauce, garlic oil and stir-fry for 1-2 mins more until the veg is warmed through.
Serve the pork with the greens, a drizzle of any resting pork juices and rice or noodles, if you like.