If using refrigerated rice cakes, soak in warm water for 15 mins. Place a large frying pan over high heat and pour in the stock (or water). Bring to a boil, then add the gochujang, soy sauce, sugar and corn syrup. Stir and reduce to a medium heat.
Tip the rice cakes and fish cakes into the pan of sauce. Simmer for 10 mins until the rice cakes are soft and the sauce has thickened and clings to the rice cakes. Stir in the spring onions and serve immediately.