Drain the oil from the canned tuna using a sieve.
Finely chop the onion and green onion.
Heat cooking oil in a pan and sauté the onion and green onion.
Add gochujang (Korean chili paste), sugar, soy sauce, and minced garlic, then stir-fry.
Add the tuna and stir-fry together.
Add rice and mix well with the seasoning, stir-frying together.
Transfer the finished spicy tuna mayo rice to a bowl.