Wash the cabbage thoroughly and slice it thinly.
Cut the onion and carrot into appropriate sizes.
Add cooking oil to a pan and stir-fry the onion and carrot.
Add the cabbage and stir-fry until it softens.
Drain the oil from the canned tuna and add it to the pan, stir-frying together.
Season with soy sauce, pepper, etc.
Place the sautéed cabbage tuna mixture over rice.
Add your desired toppings (seaweed flakes, eggs, etc.).