Prepare brown rice so that it's fluffy and not sticky.
Rinse the aged kimchi in water, squeeze out excess moisture, and slice it thinly.
Drain the oil from the tuna can and separate the tuna.
In a frying pan, stir-fry aged kimchi and tuna with a bit of sesame oil over medium heat.
Place a sheet of seaweed on a sushi rolling mat, then spread the brown rice evenly.
Top the rice with the stir-fried kimchi tuna filling.
Add perilla leaves and roll it up tightly.
Cut into bite-sized pieces and serve.