Cut the fish cakes and enoki mushrooms into bite-sized pieces.
Julienne the onion and green onion.
Heat cooking oil in a pan and stir-fry the onion and green onion.
Add the fish cake and stir-fry, then add the enoki mushrooms.
Season with soy sauce, sugar, and pepper.
Stir-fry until everything is well combined, then transfer to a plate.