Prepare the pork by cutting the tenderloin into bite-sized cubes and thinly slicing the pork belly into small strips.
In a small mixing bowl, whisk together the gochujang, tamari, and sesame oil until smooth.
Place a large skillet or wok over medium-high heat. Add the pork belly strips and cook until the fat renders and the edges become golden and crispy.
Add the pork tenderloin cubes to the skillet, seasoning with sea salt and black pepper. Sear for 4-5 minutes until browned on all sides.
Stir in the shredded cabbage, sliced bell peppers, minced ginger, and garlic. Sauté for 3 minutes until the vegetables are tender yet retain a slight crunch.
Pour the gochujang sauce over the mixture and toss vigorously for 1 minute to ensure everything is evenly coated and the sauce has thickened slightly.
Remove from heat and garnish with sesame seeds before serving.