Wash onion, carrot, potato, and zucchini thoroughly and cut into bite-sized pieces.
Slice the mushrooms and green onion into bite-sized pieces as well.
Add cooking oil to a pot and sauté the onion and green onion.
Add the remaining vegetables in order and continue stir-frying.
Pour in 400ml of water and bring to a boil.
Season with salt and pepper to taste.
Simmer over low heat for 10 minutes.