Thinly slice the cabbage.
Julienne the onion and carrot as well.
Heat cooking oil in a pan and stir-fry the cabbage, onion, and carrot.
Once the vegetables are softened, add the tuna and stir-fry together.
Season with soy sauce, sugar, and pepper.
Place the stir-fried ingredients on top of the rice.
Sprinkle with sesame seeds and chopped green onions to finish.