Grate zucchini, slice onions and mushrooms and dice parsley. Heat wok.
Saute zucchini in 1/2 tablespoon of olive oil. Add 1 cup of water, cover and simmer for 10 minutes. In a saucepan add the rest of the oil and saute onions. When transparent add the mushrooms and parsley, lower heat and add 2 cups water to almost cover vegetables. Place a lid on top and simmer for 10 minutes.
Blend zucchini; add to the cooked vegetables. Cover with the remaining water and bring to a boil. Season with salt and simmer a further 5 minutes. Mix miso with a little soup broth to form a paste. Add back to soup and let stand for 2-3 minutes. Serve with fresh dill garnish.