Cut chicken breast into bite-sized pieces and season lightly.
Finely chop kimchi and onion.
Heat cooking oil in a pan and sauté the onion and kimchi.
Add the chicken breast and stir-fry until cooked through.
Add rice and stir-fry until all ingredients are well mixed.
Season with soy sauce, sesame oil, and pepper to taste.
Plate and sprinkle sesame seeds on top.