Heat pan to medium high heat. Add pork belly and onion. Cook for 2-3 minutes stirring until pork and onion are slightly browned. If there is excess oil from the pork belly, remove it before adding kimchi.
Add kimchi and cook for 3-5 minutes until kimchi is almost turning translucent.
Add ginger and green onion and cook for 1-2 minutes to remove rawness.
For the white part of the green onion, cut into quarters lengthwise, otherwise it will be too thick for the stir-fry. Then cut into 2" pieces.