Wash the cabbage thoroughly and slice it thinly.
Slice the onion thinly.
Cut the carrot into thin slices.
Heat cooking oil in a pan and stir-fry the onion and carrot.
When the onion turns translucent, add the cabbage and stir-fry together.
Drain the oil from the canned tuna and add it to the pan.
Add a little salt to season.
Serve the stir-fried ingredients over rice to finish.