Cut the fish cakes into bite-sized pieces.
Slice the onion and green onion thinly.
Heat cooking oil in a pan and stir-fry the onion and green onion.
Add the fish cakes and stir-fry together.
Add gochujang (Korean red chili paste), red pepper flakes, soy sauce, sugar, and minced garlic, then stir-fry.
Add a little water and simmer until the fish cakes absorb the sauce.
Drizzle with sesame oil and sprinkle with sesame seeds.