Slice pork belly into 1-inch bite-sized pieces and set aside.

In a medium bowl, combine soy sauce, gochujang, sesame oil, rice vinegar, brown sugar, minced garlic, and grated ginger (if using). Whisk until the marinade is smooth and well combined.

Add the sliced pork belly to the marinade, ensuring all pieces are thoroughly coated. Cover the bowl and refrigerate for at least 30 minutes, or for up to 2 hours for deeper flavor penetration.

Heat a large non-stick pan or cast-iron skillet over medium-high heat. You won't need extra oil as the pork belly will render its own fat.

Add the marinated pork belly to the hot pan, taking care not to overcrowd it. Cook in batches if necessary to ensure even crisping.

Cook for 8-10 minutes, flipping the pieces occasionally, until they are golden brown, beautifully crispy on all sides, and cooked through. The internal temperature should reach 145°F (63°C).

Remove the cooked pork belly from the pan and transfer it to a plate lined with paper towels to drain any excess fat.

Garnish the crispy pork belly bites generously with sesame seeds and freshly sliced green onions.

Serve immediately and enjoy as a flavorful appetizer or a satisfying main course with your favorite Korean sides.