The night before, butterfly the Boneless Pork Shoulder (6 pound) by cutting the meat open so that it lays in a flat even thickness. Cut through the thick part of the meat, horizontally to almost the edge. Unfold it for a broad flap of meat, about 1 1/2-2 inches thick.
Place pork on a baking sheet and liberally spread the whole jar of Stubb's® Pork Spice Rub (1 jar) over both sides of the flesh, massaging it in with your hands. Cover with plastic wrap and refrigerate overnight.
The next day, soak the hickory wood chips in a bowl filled with water for an hour.
Combine Apple Cider Vinegar (1 cup), Granulated Sugar (2 teaspoon) and Kosher Salt (1 tablespoon) in a cup. Stir until sugar and salt have dissolved. Place the Red Onion (1) in a small bowl and cover with the vinegar mixture.
Set aside for at least an hour and up to 2 to 3 hours.
In a small saucepan, combine Stubbs® Spicy Bar-B-Q Sauce (3/4 cup), Stubb's® Sticky Sweet Bar-B-Q Sauce (3/4 cup), Unsweetened Pineapple Juice (1/4 cup) and Worcestershire Sauce (8 drop).
Cook, uncovered until sauce reduces and thickens, about 15 minutes.
Add the chips to the smoker box and place over one of the burners. Preheat your gas grill with a closed lid and wait for a soft white smoke to begin emanating from the grill for about 10 to 15 minutes.
Turn off all the burners except the one directly under the smoker box, for indirect cooking. Then place the pork opposite the smoker box, so it's not getting direct heat. Cook for about an hour at 350 degrees F (180 degrees C) without opening the lid.
After an hour, use the meat thermometer to check the temperature of the meat by inserting it into the thickest portion. When it reaches 125 degrees F (51 degrees C), turn the rest of the burners on and use direct heat for the remainder of the cooking.
Grill the pork, watching for flare ups and turning the meat once or twice while cooking. You want to achieve an internal temperature of 165 degrees F (74 degrees C) before pulling it off the grill.
During the last 15 minutes of cooking, liberally brush the barbecue sauce over the meat. Cook for 5 or so minutes, then flip the meat and brush sauce on the other side. Cook for 5 minutes and flip again, so the sauce forms a nice crust.
When the pork reaches 165 degrees F (74 degrees C), transfer it to a cutting board and tent with tin foil. Let the meat rest for 15 minutes so the juices can redistribute throughout the flesh.
Meanwhile, grill the Pineapple (1) until you get some nice grill marks, flipping halfway through for about 5 to 8 minutes. Transfer to a platter.
Using a very sharp knife, slice the pork as thinly as possible across the grain.
Place a pineapple ring on the bottom of each of the Buns (16) and top with a generous serving of sliced pork, followed by extra barbecue sauce, pickled onions, and Fresh Cilantro (to taste).