Prepare filling:
1. Dice or cut mushrooms into shreds.
2. Boil vegetables in water,squeeze dry, and use only the leaves. Drain the vermicelli and cut into shorter pieces.
3. Heat sesame oil in wok,and stir fry all the ingredients with seasonings til sauce is absorbe by ingredients.Put in the sesame seeds and set aside to let cool.
The bun:
1. Remain 1/2 cup of the flour, and knead the rest with water to form soft smooth dough. Place in container, and let rest until it doubles in size.
2. Knead for another 10 mins on floured surface and divide them into 20 equal portions. Roll into ball, press flat, the wrap in fillings.
3. Steam in steamer for about 10mins.