Pat dry your pork butt with paper towels. Slice pork butt into two long equal pieces with enough fat marbling through each piece. Approximate dimensions: 2 inches thick x 3 inches wide and 6 inches long. It's okay if you're off by a few centimeters.
In a medium size bowl, combine Marinade ingredients and mix until smooth. You may need a fork to mash the fermented red bean curd.
Place both pieces of pork in a Ziploc bag or large bowl. Pour marinade over the pork and ensuring most of pork is covered by the marinade. If you're using a Ziplock bag, squeeze out any air pockets. If you're using a large bowl, cover with a lid or plastic wrap. Marinate for at least 6 hours or overnight in the fridge.
In a small bowl, combine Basting Glaze and mix well until smooth.
Lightly spray vegetable oil or any neutral oil into air fryer basket. Place marinated pork into air fryer basket in a single layer giving each piece enough space for air circulation.
Brush basting glaze on top of each pork piece and along the sides. Air fry for 16 minutes in total at 400 F, flipping over and basting at every 4-minute mark. Until you reach an internal temperature of 145 F or until juices run clear. If you'd like it more charred, air fry for another 2 minutes but no more than that.
Remove the pork from air fryer basket and place on cutting board. Let this sit for 10 minutes before cutting to keep in the juices.
Slice on a bias into 0.5 - 0.75 cm thick pieces. Enjoy!