Blanch the tofu noodles and rice noodles separately in boiling water for 2 minutes each.
Cut chicken breast into bite-sized pieces and season with salt and pepper.
Heat cooking oil in a pan and stir-fry the chicken breast.
When the chicken is cooked, add kimchi and onion, and stir-fry together.
Add spicy gochujang, soy sauce, and minced garlic, then mix well.
Add the tofu noodles and rice noodles, then stir-fry until all ingredients are evenly combined.
Finish by drizzling sesame oil and sprinkling sesame seeds on top.