Rub the pork shoulder with sea salt, black pepper, cumin, oregano, and garlic powder until evenly coated.
Place the seasoned pork in a slow cooker and pour the orange juice and water around the base.
Cover and cook on low for 8 hours or high for 4 hours until the meat is tender enough to shred easily with a fork.
Remove the pork from the slow cooker and shred it using two forks, discarding any large pieces of excess fat.
Heat a non-stick skillet over medium-high heat and add the shredded pork, pressing it down with a spatula for 2-3 minutes to create crispy, golden-brown edges.
In a separate dry pan, warm the corn tortillas for 30 seconds per side until soft and pliable.
Divide the crisped carnitas evenly between the two tortillas.
Top each taco with finely diced white onion, chopped fresh cilantro, and thinly sliced radishes.
Serve immediately with a fresh squeeze of lime juice over the top.