Slice the frozen fish cakes into bite-sized pieces after soaking them in boiling water for about 30 seconds. In a small bowl, combine the sauce's components.
Onion, green onion segments, and garlic are added to a large skillet that is heating up the oil over medium heat. Cook the fish cakes for around 2 minutes while stirring continually after cooking the aromatics for a few minutes.
Pour the sauce in and let it simmer for a couple of minutes, or until it has reduced. Sesame oil and the saved green onions are added at the end. Enjoy with sesame seeds as a garnish!