Cut the pork belly into bite-sized pieces, and finely chop the green onions and onion.
Add just a tiny bit of oil to the pan and cook the pork belly thoroughly first.
Once one side turns golden brown, stir everything together and add a splash of mirin to get rid of any gamey smell.
Add the onion and green onion, and stir-fry until evenly combined.
Once everything is well mixed, add the gochugaru and stir-fry slowly over low heat to draw out the chili oil.
Once the chili oil has formed, add the doenjang into it and stir-fry over low heat for 1 minute.
Mix the sautéed doenjang thoroughly with the meat, then add the sugar and stir-fry over medium heat. Stir-frying for 2-3 minutes helps the seasoning soak into the meat for even better flavor.
Add the minced garlic and stir-fry for 1-2 minutes, then pour in the water and simmer over medium heat, adjusting the consistency to your liking. Season with salt and pepper as needed.