Combine the kosher salt, oregano, cumin, black pepper and chili powder in a small bowl.
Rub the mixture onto the pork tenderloin and place the pork into the slow cooker.
Add the can of chipotles in adobo sauce, 2 cups of fresh diced pineapple, ½ cup of red onion, garlic, lime juice and apple cider vinegar to a food processor, or blender.
Blend until smooth.
Pour this mixture over the pork in the slow cooker, then pour the beer over the top.
Cover and slow cook for 3-4 hours on high or 6-8 hours on low.
Remove from the crock pot and grab two forks or meat claws to quickly and easily shred the meat.
Flip the meat claws over and easily transfer the meat back into the crock pot.
Toss the meat with the sauce in the crock pot then serve the meat on tortillas, topped with the remaining pineapple and red onion, as well as cilantro and lime wedges.