Cut the chicken breast into bite-sized pieces.
Slice the onion, cabbage, carrot, and green onion.
Mix gochujang, soy sauce, minced garlic, red pepper powder, sugar, pepper, and sesame oil to make the marinade.
Put the chicken breast and vegetables into a bowl and mix them well with the marinade.
Add cooking oil to a pan and put in all the ingredients.
Stir-fry the ingredients over medium heat until cooked.
When the chicken breast is done, sprinkle sesame seeds on top to finish.