Cut the chicken into bite-sized pieces.
Chop onion, green onion, sweet potato, and cabbage into pieces suitable for eating.
In a bowl, combine chili powder, soy sauce, minced garlic, gochujang, sugar, pepper, and sesame oil to make the marinade.
Add the marinade to the chopped chicken and vegetables and mix well.
Heat cooking oil in a pan over medium heat and stir-fry the chicken and vegetables.
When all the ingredients are cooked through, it's ready to serve.