In a bowl mix together cumin, pepper, salt, oregano, garlic powder and chili powder. Rub all over pork and let set in refrigerator covered overnight or for at least an hour.
Add a drizzle of olive oil and onions to a hot frying pan. Cook for about 5 minutes until starting to soften.
Using Pam spray inside of slow cooker. Add onions, pork, lime juice and beer. Drizzle olive oil over top and let it cook up to 8 hours for low or 5 hours on high. The pork is done with it flakes easily.
Remove from slow cooker and let sit for a few minutes on a baking sheet. Shred with two forks and add to serving plate or bowl. Pour additional juices from slow cooker over top including onions.
Serve with your favourite barbecue sauce and fresh buns.
Since we didn't have a slaw to go with the pulled pork, we put out some fresh toppers including: sliced red onion, cilantro, sliced fresh jalapenos