Season the pork shoulder evenly with ground cumin, dried oregano, sea salt, and black pepper.
Place the seasoned pork in a slow cooker along with the orange juice, lime juice, and minced garlic cloves.
Cover and cook on low for 8 hours until the meat is tender and easily pulls apart with a fork.
Remove the pork from the slow cooker, shred it thoroughly, and discard any excess cooking liquid.
Heat a large non-stick skillet over medium-high heat and add the shredded pork, pressing it down to sear until the edges become golden and crispy.
Warm the corn tortillas in a separate dry pan for 30 seconds per side until soft and pliable.
Divide the crispy pork between the tortillas and top with diced red onion, sliced radishes, and fresh cilantro.
Finish each taco with a dollop of plain Greek yogurt for a cool, creamy contrast.