Rub the pork shoulder with cumin, dried oregano, sea salt, and black pepper until evenly coated.
Place the seasoned pork in a slow cooker along with the smashed garlic cloves and orange juice.
Cover and cook on low for 8 hours or until the meat is tender enough to be easily shredded with a fork.
Remove the pork from the slow cooker, shred it with two forks, and discard any large pieces of excess fat.
Heat a non-stick skillet over medium-high heat and add the shredded pork, pressing down to crisp the edges for 3-4 minutes.
Warm the corn tortillas in a dry pan or over an open flame until pliable and slightly charred.
Divide the crispy pork between the tortillas and top with diced red onion, chopped cilantro, and thinly sliced radishes.
Serve immediately with a fresh squeeze of lime juice over the top.