In a small bowl, mix the ground cumin, dried oregano, sea salt, and black pepper.
Rub the spice mixture evenly over all sides of the pork shoulder.
Place the seasoned pork in a slow cooker along with the minced garlic and orange juice, cooking on low for 6 to 8 hours until the meat is fork-tender.
Once cooked, remove the pork from the slow cooker and shred it using two forks, discarding any excess fat.
Heat the avocado oil in a large skillet over medium-high heat.
Add the shredded pork to the skillet in a single layer and press down with a spatula, searing for 3 to 5 minutes until the edges are golden and crispy.
While the pork crisps, whisk together the Greek yogurt and the juice from the lime to create a zesty crema.
Warm the corn tortillas in a dry pan or over an open flame until pliable.
Assemble the tacos by dividing the crispy pork between the tortillas, then top with diced white onion, fresh cilantro, and a drizzle of the lime crema.