Cut tofu, zucchini, onion, and shiitake mushrooms into bite-sized pieces.
Add doenjang (soybean paste) and water into a pot and bring to a boil.
Once it starts boiling, add zucchini, onion, and shiitake mushrooms and cook over medium heat.
Add tofu and minced garlic, then simmer a bit longer.
Add Cheongyang chili pepper and green onion, boil for another 2-3 minutes, and finish.