In a small bowl, combine dried oregano, ground cumin, black pepper, salt, and chili powder. Rub this spice mixture evenly over the pork shoulder.

Place the seasoned pork shoulder in the slow cooker. Add chopped onion, minced garlic, and diced jalapeno pepper. Pour in fresh orange juice.

Cover the slow cooker and cook on low for 8 to 10 hours or high for 5 to 6 hours until pork is fork-tender.

Once done, transfer the pork to a board and shred it using two forks. Optionally return to slow cooker to keep warm.

For extra texture, preheat broiler, spread shredded pork on a baking sheet, and broil for 5 to 10 minutes.

Warm tortillas and assemble tacos by filling with shredded carnitas, then top with red onion, cilantro, and a squeeze of lime.