Cut the pork into 1 inch thick slices. Using a fork, stab the pork on all sides to tenderize and allow the marinade to penetrate deeper.
In a bowl, mix the sauce marinade ingredients together.
In another bowl, set aside 2 tbsp of the sauce marinade. Add honey and water and mix well. This honey marinade will be used to baste the pork while it's cooking.
In a Ziploc bag or container, add the pork and sauce marinade. Rub the marinade into the pork to coat well. Let it marinate in the fridge for 12 to 48 hours (the longer the better!).
Preheat the air fryer at 400F/205C. Place the marinated pork in the air fryer making sure there is enough space on all sides.
Cook for 3 minutes, then baste with the honey marinade. Flip and baste the other side. Cook for another 3 minutes. Repeat 2 more times. Cook for a total of 12 minutes. Depending on the thickness of your pork, you may need to cook it for another minute or two.
Remove the char siu from the air fryer and let it rest for 10 minutes before cutting.
*Optional* Save the sauce drippings from the bottom of the air fryer pan/tray and pour it over the cooked char siu.
Serve with jasmine rice and your favorite vegetables!