Prepare the grill for indirect cooking over medium-low heat (250° to 350°F).
In a small bowl mix all the rub ingredients.
Make shallow incisions all over the pork and insert the garlic slivers. Rub the pork on all sides with the rub. Place in a large grill-proof Dutch oven.
Grill the pork over indirect medium-low heat, with the lid closed, until an instant-read thermometer inserted into the thickest part of the pork shoulder registers 195° to 200°F, and the meat is falling apart tender, about 4 hours, turning occasionally. Remove from the grill, and rest indoors until cool enough to handle. Then shred the pork.
Pour off all but 2 tablespoons cooking juices from the Dutch-oven and place on the stove over medium heat. Add the pineapple juice and deglaze the pot, scraping up any brown bits. Whisk in the soy sauce, brown sugar, and salt. Add the cabbage and cook until bright in color and just wilted, 3 to 4 minutes, stirring frequently. Add the shredded pork and stir to combine.
Serve the pork with cooked basmati rice and butter leaves for wrapping. Garnish with the scallions, cilantro, and hot chili-garlic sauce, such as Sriracha.