Finely chop the tuna, onion, and green onion.
In a bowl, mix the tuna, onion, green onion, doenjang (soybean paste), gochujang (red chili paste), minced garlic, and sesame oil.
Heat oil in a pan and stir-fry the mixed ingredients.
Add soy sauce and sugar while stir-frying, then simmer over medium heat.
Finish by sprinkling roasted sesame seeds.