Make the batter:

1. In a mixing bowl, combine the rice flour, tapioca starch, and salt for the batter.
2. Add the boiling water to the dry mixture and stir until well combined.
3. Gradually add the room temperature water while stirring, until you achieve a smooth batter consistency. Set aside.

Filling:

1. Mash the tofu with a fork, removing excess water.
2. Soak the wood-ear mushrooms in warm water until they soften, then drain and finely chop them.
3. Finely chop the onion.
4. In a pan over medium heat, add a bit of oil and sauté the onion until translucent.
5. Add the tofu and wood-ear mushrooms to the pan, along with the salt and soy sauce.
6. Stir-fry the filling mixture for a few minutes until the tofu is lightly browned and the flavors are well combined. Set aside.

Dipping Sauce:

1. In a small bowl, combine the vegan fish sauce (or soy sauce), warm water, lime juice, sugar, minced red chili, and minced garlic.
2. Stir the mixture until the sugar is dissolved. Adjust the taste by adding more lime juice, sugar, or chili according to your preference. Set aside.

Make vegan Banh Cuon:

1. Heat a non-stick frying pan, brushing with some oil.
2. Ladle a thin layer of the batter onto the pan, spreading it out to form a thin and even circle.
3. Cover and cook for about 2 minutes or until the rice noodle sheet is cooked and can easily be lifted off the pan or steamer.
4. Flip the pan upside onto a flat surface. Put the pan back on the stove, spread out a thin batter, and cover with the lid to make another Banh Cuon.
5. Add a small amount of the filling mixture onto the rice noodle sheet and roll it up tightly.
6. Repeat the process with the remaining batter and filling.

Serving:

1. Arrange the banh cuon rolls on a serving plate. Serve with the greens and dipping sauce!