Prepare the rice.
Finely chop fillings such as Spam, pickled radish, and kimchi.
Stir-fry the fillings in a heated pan.
Mix the stir-fried fillings with rice, sesame oil, and salt.
Shape the rice into a ball and put cheese in the center.
Wrap the rice ball tightly with plastic wrap or foil to maintain the shape.
Finish with seaweed or sesame seeds.