Let's cook.
In a medium bowl, combine the gochujang, gochugaru, soy sauce, sugar, sesame oil, minced garlic, and grated ginger to create the marinade.
Add the thinly sliced pork belly to the marinade, ensuring each piece is well coated. Marinate for at least 15 minutes at room temperature, or up to 30 minutes in the refrigerator.
Heat a large skillet or wok over medium-high heat. Add the marinated pork belly and sliced onion.
Stir-fry the pork and onion for 8-10 minutes, or until the pork is cooked through and slightly caramelized, with no pink remaining.
Remove from heat and transfer the Korean Spicy Pork Belly Stir-fry to a serving platter. Garnish generously with chopped green onion.
Serve immediately with steamed white rice and your favorite banchan (Korean side dishes).
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