Cube the pork tenderloin and pork belly into 1-inch pieces and place them in a medium glass bowl.
In a small jar, whisk together gochujang, coconut aminos, rice vinegar, sesame oil, grated ginger, and minced garlic.
Pour half the marinade over the pork pieces, tossing to coat thoroughly, and let it marinate for 20 minutes.
Cut the red bell pepper into 1-inch squares and chop the green onions into 1-inch pieces.
Thread the marinated pork tenderloin, pork belly, bell peppers, and green onions onto skewers, alternating for variety.
Season the assembled skewers with sea salt and black pepper.
Heat a grill or cast-iron grill pan over medium-high heat and lightly coat with a high-smoke point oil.
Grill the skewers for 3-4 minutes per side until the pork is cooked through and the belly fat is crispy and golden.
Brush the remaining marinade over the hot skewers just before serving for a vibrant finish.