Cut the pork loin and pork belly into 1-inch cubes and place them in a medium mixing bowl.
In a small bowl, whisk together the gochujang, tamari, sesame oil, minced ginger, and minced garlic to create the marinade.
Pour the marinade over the pork, tossing well to coat every piece, and let it sit for at least 15 minutes.
Slice the zucchini into half-inch rounds and the red bell pepper into 1-inch squares.
Thread the marinated pork loin, pork belly, zucchini, and peppers onto wooden or metal skewers, alternating meat and vegetables.
Season the vegetable portions of the skewers with sea salt and black pepper.
Heat a grill pan or outdoor grill over medium-high heat and lightly grease with a touch of oil if needed.
Grill the skewers for 3-4 minutes per side, or until the pork is cooked through and the edges are slightly charred and caramelized.
Remove from heat and let rest for 2 minutes before serving.