Shred the cabbage.
Thinly slice the onion.
Julienne the carrot.
Heat cooking oil in a pan and sauté the onion and carrot.
Add the cabbage and stir-fry until wilted.
Add the tuna and stir-fry together.
Season with soy sauce, sugar, and pepper.
Place the sautéed ingredients on top of rice.
Sprinkle sesame seeds and seaweed flakes as desired.