Warm oil in large skillet on high. Season Pork Shoulder with Salt and Pepper. Brown Pork Shoulder on all sides, roughly 2 minutes per side. Place in Slow-cooker. Cover with chopped onion and jalapeño.
Mix pineapple juice, lime juice, soy sauce, brown sugar, chile powder, paprika, garlic and black pepper together. Pour over pork shoulder.
Cover and cook on low for 8 hours. Roughly chop the pork and add back into the cooking liquid to warm through.
Grilled Pineapple Salsa:
On medium high heat, grill jalapeños, red pepper and red onion until just charred. Set aside to cool and then dice into like-sized pieces. While you chop, grill pineapple slices until charred, then allow to cool and dice.
In a large bowl, mix together pineapple, tomatoes, jalapeños, red pepper, onion and cilantro with lime juice. Salt and Pepper to Taste. Place in refrigerator to cool.
Warm Non-GMO Cornflowers Tortillas on open flame until slightly charred. Fill with sweet pork and top with shredded red cabbage, grilled pineapple salsa, crumbled cotija cheese and cilantro. Serve with a lime wedge.