Cut the pork belly into three large pieces. Place them in a pot with enough water to cover. Add 2 tbsp doenjang, 3-4 garlic cloves, 2 tbsp soy sauce, 1/2 spring onion, 2-3 bay leaves, and 1/2 tbsp ginger powder. Boil on high heat for 5 minutes, then reduce to medium-low heat, cover, and simmer for 20 minutes.

Prepare the soy sauce mixture: Combine 6 tbsp soy sauce, 2 tbsp minced garlic, 1/2 tbsp ginger powder, 2 tbsp mirin, 2 tbsp corn syrup, 2 tbsp sugar, and a pinch of black pepper. Add 1/2 cup of the pork broth to the mixture.

Check the pork by piercing it with a skewer. If no blood comes out, it's done. If blood is visible, cook for a few more minutes.

Remove the pork from the broth and pat it dry. Heat a pan with oil and sear the pork on both sides until golden brown.

Pour the prepared soy sauce mixture into the pan with the seared pork. Simmer and reduce the sauce while coating the pork.