Cut the onion, green onion, and kimchi into bite-sized pieces.
Slice the beef brisket into pieces that are easy to eat.
Add the beef brisket to a pot and stir-fry over medium heat.
When the beef is about half-cooked, add the kimchi and stir-fry together.
Add Korean chili powder and minced garlic, and continue stir-frying.
Pour in 300ml of water and bring to a boil.
Add the onion, green onion, and tofu, then simmer for 10 minutes.
Taste and adjust the seasoning with salt or soy sauce if needed.