Wash the napa cabbage thoroughly and cut it into bite-sized pieces.
Finely chop the onion and carrot.
Heat cooking oil in a pan and stir-fry the onion and carrot.
Add tuna and stir-fry, then add the napa cabbage and cook together.
Season with soy sauce, sugar, and pepper.
Place the stir-fried ingredients over rice.
Garnish with seaweed flakes and sesame seeds.