Mix the rice flour and tapioca starch with 4 1/4 cups water (1 liter). Stir well in one direction. Add 2 tablespoons vegetable oil (30 ml) to the batter. Let the batter rest for 1 to 1.5 hours.

Soak the wood ear and shiitake mushrooms until soft, then chop finely. Add vegetable oil to a pan. Sauté the dried shallots, then add 7 ounces ground pork (200 grams) and cook until done. Once the pork is cooked, add the chopped mushrooms and stir well.

After 40 minutes, the batter is ready. Heat a nonstick pan. Brush a thin layer of oil onto the hot pan. Use a ladle to pour a thin layer of batter into the pan. Cover and cook for 30 seconds until the crepe is set. Brush a thin layer of oil onto a cutting board and gently flip the pan so the crepe falls onto the board.

Place a spoonful of filling onto the crepe and quickly roll it up. Repeat steps 3 and 4 until all the batter is used.

Make the dipping sauce by mixing 1 part fish sauce, 3 parts sugar, 5 parts water, 2 parts white vinegar, minced garlic, and black pepper. Slice shallots (you can sun-dry them for half a day to make them crispier), then fry them in hot oil over low heat for 5 minutes. Note: When the shallots start turning from white to golden, turn off the heat and remove the pan to prevent burning.

Arrange the banh cuon on a plate, sprinkle with fried shallots, and serve with the dipping sauce.