Soak wooden skewers in water for at least 20 minutes to prevent them from burning on the grill.
Cut the pork tenderloin, pork belly, and red bell pepper into uniform 1-inch cubes.
In a small mixing bowl, whisk together the gochujang, coconut aminos, rice vinegar, sesame oil, and garlic powder until smooth.
Season the pork cubes evenly with sea salt and black pepper.
Thread the pork tenderloin, pork belly, and bell pepper pieces onto the skewers, alternating the ingredients.
Preheat a grill or a cast-iron grill pan over medium-high heat and lightly grease with a high-smoke point oil if needed.
Place the skewers on the grill and cook for 8 to 10 minutes, turning every few minutes to ensure even browning and charring.
During the final 2 minutes of grilling, use a brush to coat the skewers generously with the gochujang glaze on all sides.
Remove the skewers from the heat once the pork is cooked through, sprinkle with toasted sesame seeds, and serve immediately.