Cut the pork belly into bite-sized pieces.
Slice the onion and green onion into easy-to-eat pieces.
Heat oil in a pan and stir-fry the pork belly.
Add the onion and green onion, and stir-fry together.
Season with soy sauce, sugar, mirin, and pepper.
Place the stir-fried pork belly and vegetables over rice.
Finish by sprinkling sesame seeds and chopped green onions.