Prepare the rice, kimchi, tuna, and seaweed flakes.

Wash the aged kimchi and squeeze out excess water. Chop finely.

Drain the tuna and mix it with the chopped kimchi in a large bowl.

Add mayonnaise, salt, sugar, sesame oil, black pepper, and sesame seeds to the bowl. Mix well.

Season the rice with 2 pinches of salt and 2 tbsp of sesame oil. Mix gently using the edge of a spoon.

Take a handful of rice and flatten it in your palm. Place a spoonful of the tuna-kimchi mixture in the center.

Take another small portion of rice, flatten it, and cover the filling to form a ball.

Roll the rice ball in seaweed flakes until evenly coated.