Cut the rice cakes and fish cakes into bite-sized pieces.
Thinly slice the onion and green onion.
Add water, gochujang (Korean chili paste), chili powder, sugar, soy sauce, and minced garlic to a pan and bring to a boil.
Once the sauce boils, add the rice cakes, fish cakes, and onion.
Simmer over medium heat until the rice cakes become soft.
Add the green onion and boil once more to finish.