Shred the cabbage into thin strips.
Slice the onion and carrot thinly.
Heat cooking oil in a pan, then sauté the onion and carrot.
Add the cabbage to the pan and stir-fry together.
Drain the oil from the canned tuna and add the tuna to the pan. Stir-fry.
Season with soy sauce, salt, and pepper.
Spoon the stir-fried mixture over steamed rice to finish.