Cut tofu and vegetables into bite-sized pieces.
Add sesame oil to a pot and stir-fry garlic and green onions.
Add red pepper flakes and cook on low heat to bring out the aroma.
Pour in water and bring to a boil.
Add soft tofu, mushrooms, zucchini, and onion, and continue boiling.
Season with salt or soup soy sauce to taste.
Add egg and finish boiling.