Cut the zucchini and onion into bite-sized pieces.
Cut the tofu into large cubes and slice the green onion thinly.
Heat cooking oil in a pan and stir-fry the green onion to bring out its aroma.
Add the zucchini and onion and continue stir-frying.
Dissolve gochujang (Korean chili paste) in water, then add it to the pan.
Add tofu and simmer over low heat until there's a small amount of broth left.
Season with soy sauce, minced garlic, and pepper. Let it reduce until flavors blend.