Cut the tofu into bite-sized pieces.
Slice the onion, green onion, and potato.
Add cooking oil to a pot and sauté minced garlic and gochujang.
Add onion and potato, and continue to stir-fry.
Pour in water or broth and bring to a boil.
When the potato is cooked, add the tofu.
Season with soup soy sauce, salt, and black pepper.
Add green onions and simmer briefly.