Have the water, soy sauce and mirin all measured into a glass so they can be added quickly together to the wok. Dissolve the miso into the vegetable stock. Keep aside ready to be added later.
Heat the oil in a wok. Stir fry asparagus and snow peas for 2 minutes.
Add tofu, mirin, soy sauce and water, stir fry for a further minute.
Add stock, miso and spinach. Cook for 2-3 minutes, or until the spinach has wilted. Pour into a bowl. Enjoy!