Preheat your Yoder Smokers YS640s Pellet Grill to 300ºF, set up for smoking.
Cover the pork butt in a thin layer of pineapple juice, for binder. Season all surfaces generously with Cattleman’s Grill Mexicano Seasoning. Let rest until the seasoning appears wet on the surface.
Place the pork butt on the second shelf of the smoker, near the smoke stack.
Place your tomatillos, tomatoes and white onion on the second shelf of the smoker, as well.
Smoke the salsa ingredients for one hour, then remove from the smoker. Continue smoking the pork butt.
To make the salsa, place the smoked tomatillos, tomatoes and white onion (rough chopped) in the pitcher of a Vitamix Blender. Add there remaining ingredients and blend until smooth. Transfer to a jar or sealable container and store in the refrigerator until ready to serve.
When the pork butt has formed a dark brown/mahogany, crunchy bark (about 4 hours into the cook), Remove from the smoker and place on top of two large sheets of heavy duty foil. Turn up the edges of the foil and pour about 3/4 cup pineapple juice over the pork butt. Then wrap tightly in both sheets of foil. Return the pork to the smoker.
Continue cooking the pork butt until the blade bone easily slides out of the muscle when pulled on. The internal temperature will be over 205ºF. The pork should easy shred by hand.
Wearing cotton gloves covered with nitrile gloves, shred the pork by hand, tossing it in the braising liquid in the bottom of the foil wrap. The shredded pork will soak up all of the liquid.
Slice yellow onion about 1/4” thick, then cook in a cast iron skillet over medium heat with spray duck fat and kosher salt until softened and browned around the edges.
Toast the corn tortillas in a thin layer of spray duck fat, in a clean cast iron skillet, just until small brown spots appear. The tortillas should be pliable, not crunchy.
To assemble the tacos, start with two corn tortillas, stacked on on top of the other. Add a generous helping of pulled pork. Spoon the Smoked Arbol Salsa over the pork, then top with the griddled onions and cotija cheese.