Rinse and dry the pork shoulder, rub all over with salt and pepper. Combine the Rub ingredients then rub all over the pork. Place the pork in a slow cooker, top with the onion, jalapeño, minced garlic and squeeze over the juice of the oranges. Slow Cook on low for 10 hours or on high for 6 hours. Pork should be tender enough to shred. Remove from slow cooker and let cool slightly. Then shred using two forks.
To Crisp: Heat 1 Tsp of oil in a large non stick pan over high heat. Spread pork in the pan, drizzle over some juices. Wait until the juices evaporate and the bottom side is golden brown and crusty. Turn and just briefly sear the other side - you don't want to make it brown all over because then it's too crispy, need tender juicy bits. Remove pork from skillet. Repeat in batches, don't crowd the pan. Just before serving, drizzle over more juices and serve hot, stuffed in tacos, with salsa, onions, coriander and coriander.
Salsa: Place onion and jalapeno in the food processor first, then add remaining ingredients. Blitz to desired consistency, season.