Thinly slice the cabbage.
Slice the onion thinly.
Heat cooking oil in a pan and sauté the onion.
When the onion becomes translucent, add the cabbage and stir-fry.
Once the cabbage softens, add spicy tuna and stir-fry together.
Season with a little soy sauce.
Place the stir-fried mixture on top of rice.
Sprinkle with sesame seeds to finish.