Cut the beef brisket and leaf mustard kimchi into bite-sized pieces.
Stir-fry the beef brisket in a pan and season with salt and pepper halfway through.
Once the beef releases fat, add the leaf mustard kimchi and stir-fry together.
Add rice and stir-fry until all the ingredients are evenly mixed.
Season with soy sauce and sesame oil, and stir-fry well to combine.
Serve on a plate and finish by sprinkling toasted sesame seeds and chopped green onions on top.