Wash the vegetables in cold water until they are free of dirt. For the cabbage, soak them in lightly salted water and rinse 2-3 times.
Bring the pot of water to a boil and add the stock vegetables in along with the rehydrated mushrooms. Let the water come back to a boil, then turn the heat to low to simmer for 3 hours or until the vegetables are soft.
When the vegetables are soft, scoop them out using a sieve and pour in the coconut water.
Cut the toppings into smaller pieces to a size of your preference.
Add the salt, vegetable stock powder, vegetarian fish sauce and fried tofu in to season the soup.
Heat up a saucepan with oil and stir fry the fresh mushrooms with the vegetable stock powder.
Pour the cooked mushrooms into the broth pot.
Bring a large pot of water to a boil and cook the tapioca noodles for 5 minutes or until just loosened from a clump. Note: These noodles are already cooked, so putting them in hot water just helps to separate each strand. Use a spatula to gently ease them apart.
To serve Bánh Canh Chay, put the tapioca noodles in a bowl along with the toppings and heated soup. Garnish with chopped coriander, chili and a squeeze of lemon juice!