Slice the pork tenderloin into thin strips and finely dice the pork belly into small cubes.
In a small bowl, whisk together the gochujang, tamari, minced ginger, and minced garlic to create the stir-fry sauce.
Heat a large wok or cast-iron skillet over medium-high heat and add the pork belly, rendering the fat until the pieces are golden and crispy.
Add the pork tenderloin strips to the skillet, seasoning with sea salt and black pepper, and sear until browned and cooked through.
Toss in the broccoli florets and sliced bell peppers, stir-frying for 3 to 4 minutes until the vegetables are tender yet vibrant.
Pour the gochujang sauce over the pork and vegetables, then drizzle with the sesame oil.
Toss everything together for 1 minute until the glaze is thick, glossy, and evenly coats every ingredient.
Remove from heat, garnish with thinly sliced green onions, and serve immediately.