Rub the pork shoulder with chili powder, cumin, sea salt, and black pepper until evenly coated.
Place the seasoned pork in a slow cooker or heavy pot and cook until the meat is tender enough to shred with a fork.
Shred the cooked pork into bite-sized pieces using two forks.
Heat the avocado oil in a large cast-iron skillet over medium-high heat.
Add the shredded pork to the skillet in a single layer and press down firmly, searing for 3-4 minutes until the edges are golden and crispy.
Drizzle the lime juice over the crispy pork and toss gently to combine.
Warm the corn tortillas in a dry pan or over an open flame until pliable.
Thinly slice the radishes and roughly chop the fresh cilantro.
Assemble the tacos by layering the crispy pork onto the warm tortillas, followed by the shredded cabbage, sliced radishes, and cilantro.
Top each taco with a dollop of non-fat Greek yogurt as a clean alternative to sour cream and serve immediately.