Cut the kimchi and onion into bite-sized pieces.
Add tuna oil and cooking oil to a pot, then stir-fry onion, kimchi, and minced garlic.
Stir-fry until the kimchi is cooked, then add water.
Add canned tuna and simmer over medium heat.
Season with red pepper powder, soy sauce, salt, and pepper.
Add tofu and bring to a boil once more.
Add green onions and turn off the heat.