Soak four wooden skewers in water for at least 20 minutes to prevent burning.
Cut the pork tenderloin and pork belly into uniform 1-inch cubes.
In a small bowl, whisk together the gochujang, tamari, toasted sesame oil, raw honey, grated ginger, and minced garlic to create the marinade.
Place the pork cubes in a bowl, toss with the marinade until well-coated, and let sit for 15 minutes.
Dice the red bell pepper and red onion into 1-inch pieces suitable for skewering.
Thread the pork and vegetables onto the skewers, alternating between the lean tenderloin, the succulent belly, pepper, and onion.
Season the assembled skewers lightly with sea salt and black pepper.
Preheat a grill or cast-iron grill pan over medium-high heat and lightly grease with a high-smoke point oil if needed.
Grill the skewers for 3-4 minutes per side, turning occasionally, until the pork is cooked through and the glaze is beautifully charred.
Remove from heat and garnish with sesame seeds and thinly sliced green onions before serving.