Cut the chicken into bite-sized pieces and prepare the onion, green onion, rice cakes, and other ingredients.
In a bowl, make the sauce by mixing gochujang (Korean chili paste), soy sauce, minced garlic, sugar, and chili powder.
Heat oil in a pan, stir-fry the chicken, and when it's halfway cooked, add the onion and rice cakes.
Pour in the sauce and stir-fry over high heat until all the ingredients are fully cooked.
Add green onion and a final drizzle of sesame oil, give it a quick stir-fry, and finish.