In the bottom of a slow cooker, combine the beef broth, onion, garlic, chipotle peppers, lime juice, chili powder, brown sugar, cumin, paprika, dried oregano, and cayenne.
Add the pork to the bottom of the slow cooker and cook on low for 8 to 10 hours or until the pork falls apart easily with a fork (read here why I am only recommending low cooking). Remove from the slow cooker, and remove any large pieces of fat. Shred with two forks and return to the slow cooker for serving.
Serve as tacos, topped with pickled red onions, cotija cheese, and cilantro.
Video
Notes
Please note that the nutritional information only pertains to the pork itself, and does not reflect tortillas or any other toppings.