In a small bowl, whisk together the dried oregano, cumin, salt and pepper
Rub seasoning mixture onto pork shoulder on all sides
Add onion, garlic, orange juice and peel, lime juice and chipotle pepper to slow cooker
Place pork on top
Cover and cook on low for 4-6 hours or until internal temperature is 145 degrees F
Remove pork from slow cooker onto cutting board, let cool slightly
Shred pork with forks
Heat oil in large skillet on stove
Add pork and some of the juice from the slow cooker
Turn often to brown the pork until juices have evaporated
Repeat with more pork if your skillet doesn’t hold all of it
Serve immediately with tortillas and toppings
Store leftovers in refrigerator