Cut the chicken breast into small pieces and set aside.
Finely chop the kimchi and onion.
Heat cooking oil in a pan and stir-fry the chicken breast.
When the chicken is cooked, add the kimchi and onion and stir-fry together.
Add the rice and mix well with the other ingredients, stir-frying everything.
Season with soy sauce and pepper, and add sesame oil if desired.
Transfer the finished fried rice to a bowl.