Prep the vegetables - Cut zucchini, mushrooms, and onion into bite-sized pieces. Mince the garlic, chop the green onion, and cut tofu into cubes. Slice the jalapeño if using.
Make the base - Bring the water to a boil in a medium pot. Stir in the doenjang, minced garlic, and gochugaru (if using) until fully dissolved.
Cook the hearty ingredients - Add tofu, mushrooms, and onion. Return to a boil and cook until the vegetables begin to soften, about 5 minutes.
Add quick-cooking vegetables - Stir in zucchini, jalapeño (if using), and green onion. Simmer for another 3–4 minutes, until the zucchini is tender.
Serve - Ladle into bowls and serve hot with steamed rice.
