Prepare the batter: Mix 1 1/2 cups rice flour (about 180 grams), 1 cup tapioca starch (about 120 grams), and 3 cups water (about 720 ml). For larger batches, multiply as needed. Add a pinch of salt and 1 tablespoon cooking oil, stir well, and let the batter rest for 15 minutes.

For the filling: Soak wood ear mushrooms until soft, remove stems, and finely chop. Dice the onion. Heat a pan and sauté the onion until fragrant, then add ground pork and stir-fry. Season with a little sugar, bouillon powder, and pepper. Add the chopped mushrooms, cook until done, then turn off the heat and add chopped green onions. Let cool.

For the dipping sauce: Mix fish sauce, sugar, and hot water in a 1:1:2 ratio (tablespoons). Stir until dissolved, then add 1 tablespoon vinegar. Finely mince garlic and chili, then add to the sauce so they float on top. Adjust seasoning to taste.

Heat a nonstick pan over medium heat and brush with a thin layer of oil. When hot, pour in a ladleful of batter and swirl to coat the pan in a thin layer. Cover and cook for about 20 seconds until set. Flip the pan to release the crepe, then quickly pour in the next batch. Place some filling on the cooked crepe and roll it up. Repeat until all the batter is used.

Blanch bean sprouts briefly in boiling water. Slice cucumber and fresh herbs. Arrange bánh cuốn, herbs, bean sprouts, cucumber, pâté, and Vietnamese pork sausage on a plate. Sprinkle with fried shallots and drizzle with dipping sauce before serving.