Cut the tofu into large pieces.
Slice the zucchini and onion into bite-sized pieces.
Add sesame oil to a pot and stir-fry minced garlic.
Add the zucchini, onion, and shiitake mushrooms, and stir-fry.
Add chili powder and quickly stir-fry over low heat to make the seasoning.
Pour in water or kelp broth and bring to a boil.
When it starts boiling, add tofu and salt, and simmer for 5 more minutes.
Top with chopped green onions to taste before serving.