I was all ready to try to make a semi-traditional char siu with a hunk of pork belly when I remembered some leftover pineapple juice from Huli Huli Chicken, which would make a nice addition to the char siu sauce marinade.
I also opted to slow-smoke the belly over applewood rather than my traditional roasting method. This was, surprisingly, my first pork belly attempt but any anxiety was quickly dispelled when tasting the red-hued beauty that emerged after five hours in the smoker.
Though I did burn the skin a bit trying to crisp it over a fire that was packing too much heat, the charred crust did not hold back an otherwise excellent piece of pork belly. The insides were moist, tender, and juicy—that's almost a given when so much fat is involved—and the outside had a great crust that held the slightly sweet and salty flavor of the char siu sauce, providing the depth of flavor that resulted in four pounds of pork belly disappearing faster than I could have imagined.
In a medium bowl, mix together char siu sauce, pineapple juice, garlic, salt, and black pepper.
Score the skin of the pork diagonally every 2-inches, repeat in the opposite direction, making a diamond pattern. Place pork in a large resealable plastic bag and pour in marinade. Seal and toss to evenly coat. Marinate in the refrigerator for at least 4 hours to overnight.
Remove pork belly and allow to come to room temperature while preparing the smoker or grill. Fire up smoker or grill to 225°F for indirect heat, adding chunks of apple wood when at temperature. When the wood is ignited and producing smoke, place the pork in the smoker or grill, skin side up, and smoke until pork registers 160 degrees on an instant read thermometer inserted into the center of the belly, about 4 to 5 hours.
Place pork belly on a medium hot grill, skin side down, or in a broiler, skin side up, and cook until skin is crisp. Remove to a cutting board, let rest for 10 to 15 minutes, then slice and serve.