Pat pork shoulder dry. Combine the rub ingredients then rub all over the pork.
Place the pork in a slower cooker (fat cap up), top with the onion, jalapeno, minced garlic (don't worry about spreading it) and pour orange juice over the top.
Slow cook on low for 10 hours (recommended) or on high for 7 hours.
Pork should be tender enough to shred. Remove from the slow cooker and let cool slightly. Then shred using two forks or shredding claws.
Optional: Skim off the fat from the juices remaining in the slow cooker and discard.
If you have a lot more than 2 cupes of juice, then reduce it down to about 2 cups. The liquid will be salty, it is the seasoning for the pork. Set liquids aside - don't both straining onion, etc. it's super soft.