Add all of the ingredients for the marinade into a bowl and use a whisk to mix them all together.
Add the sliced pork and sliced onion to the marinade. Then use your hands to mix it all together until every piece of pork and onion slice is coated in the marinade. Set this aside for 30 minutes to 1 hour.
Cook the pork bulgogi: Get out a large walled pan, pour a tablespoon of oil into it, and place it over medium-high heat. Toss all of the sliced pork, onion, and any remaining marinade from the bowl to the pan. Saute these ingredients until the pork is cooked and slightly charred, about 10 minutes.
Plate your pork bulgogi garnish it with green onion and sesame seeds, and enjoy!