Chop the onion and green onion. Cut the ham into small pieces.

Mix the seasoning ingredients (gochujang, sugar, mirin, soy sauce) to make the sauce.

Heat tuna oil in a pan and sauté the chopped onion and minced garlic until the onion becomes translucent.

Add the prepared sauce to the pan and stir-fry until well combined.

Add the tuna to the pan and simmer until the mixture is slightly reduced.

Drizzle sesame oil and sprinkle sesame seeds over the tuna mixture. Set aside.

In a separate pan, stir-fry the ham until lightly browned.

Using the residual heat, stir-fry the green onion briefly in the same pan.