Cut chicken breast (as a substitute for gopchang), onion, bell pepper, and king oyster mushroom into bite-sized pieces.
Add olive oil to a pan and stir-fry the onion, bell pepper, and king oyster mushroom.
Add the chicken breast and stir-fry until cooked through.
Season with low-sodium soy sauce, pepper, and chili powder.
Add rice (brown rice or konjac rice) and stir-fry, mixing well with the other ingredients.
Finish by sprinkling chopped scallions on top.