1. Rub the pork shoulder with the sea salt, black pepper, ground cumin, and dried oregano.
2. Heat the olive oil in a skillet over medium-high heat and sear the pork on all sides until a golden-brown crust forms.
3. Mince the garlic and add it to the slow cooker along with the seared pork and orange juice.
4. Cover and cook on low for 7-8 hours or until the meat is tender enough to shred with a fork.
5. Remove the pork from the slow cooker, shred it, and optionally crisp it in a hot pan for 2-3 minutes for extra texture.
6. Warm the corn tortillas in a dry skillet until they are soft and pliable.
7. Thinly slice the radishes and finely dice the red onion.
8. Assemble the tacos by layering the shredded pork onto the tortillas and topping with the red onion, fresh cilantro, radish slices, and a dollop of nonfat Greek yogurt.
9. Cut the lime into wedges and serve them on the side for a fresh squeeze of juice.