Cut pork, Fuji apple, and onion into bite-sized pieces.
Add cooking oil to a pan, then stir-fry the onion and pork.
When the pork is half cooked, add Fuji apple and stir-fry together.
Add gochujang (Korean chili paste), soy sauce, minced garlic, sugar, and pepper for seasoning.
Continue to stir-fry over medium heat until the pork is fully cooked.
Finish by adding sesame oil and sprinkling sesame seeds.