Place pork shoulder in slow cooker and add cumin, onion, jalapeno, beer, apple cider vinegar, chipotle peppers, salt and pepper. Cut one orange and one lime in half and squeeze the juice into the slow cooker. Throw in the squeezed orange halves.
Cook on low heat for 9-10 hours OR high heat for about 6-8 hours, or until meat can be easily shredded with a fork.
Remove the pork from the slow cooker and place on a large baking sheet. Use a fork to shred it.
Spread it out in an even layer and drizzle it with orange juice from the second orange. Season with additional salt if required.
Place it under the broiler for about 5 minutes. Remove and stir. Broil for another 5 minutes and stir.
Repeat the process 4-5 timesuntil the pork carnitas is crisp around the edges. Broil more or less depending on preference.
For a soft, pliable corn tortilla, heat 1 tablespoon of oil with 1 tablespoon of the cooking liquid in a skillet.
Fry the tortilla until soft and lightly browned, about 1 minutes per side. Continue with remaining tortillas.
Serve pork with tortillas, orange and lime juice, diced onions, avocado and cilantro.
Notes
Use a slow cooker with a timer so you can set it and forget it while you're at work.
Broil for as little or as much as you need to depending on the desired crispness. I like a carnitas with crispy caramelized pieces so I usually broil it longer.
Fry the tortillas in a mixture of the cooking liquid and oil to make them more pliable.
The meat should shred apart easily with a fork when it is done in the slow cooker.