Make the batter: whisk together the Rice Flour, Tapioca Starch, Water and a pinch of Salt until completely smooth. Let the batter rest for at least 30 minutes so the starches hydrate and the mixture becomes glossy.
Rehydrate the mushrooms: soak the Dried Shiitake Mushrooms and Dried Wood Ear Mushrooms in hot water until soft, about 20–30 minutes. Squeeze out excess liquid (reserve a little soaking liquid for the filling if you like), then finely chop the mushrooms.
Prepare the filling aromatics: finely mince the Shallots. Heat a little Neutral Oil in a pan over medium heat and sauté the shallots until translucent and fragrant.
Cook the pork filling: add the Ground Pork to the shallots and break it up with a spatula. When it starts to brown, stir in the chopped mushrooms, a splash of Fish Sauce, a pinch of Sugar and freshly ground Black Pepper. Cook until the pork is fully done and the mixture is flavorful; finish by stirring in sliced Scallions. Taste and adjust seasoning.
Make the dipping sauce (Nước chấm): in a small bowl combine water, a generous splash of Fish Sauce, Sugar to dissolve, Lime Juice and a little Rice Vinegar. Add minced Garlic Clove and chopped Bird's Eye Chilies to taste, and adjust the sweet-sour-salty balance until bright and lively.
Set up your steaming station: bring a wide pot of water to a gentle boil and place a flat, oiled pan or a round steaming surface above it. Lightly brush the surface with Neutral Oil so the crepes won’t stick.
Steam the crepes: stir the rested batter, then ladle a thin layer onto the oiled surface, quickly spreading into a wide, thin circle. Cover and steam until the sheet turns from matte to translucent and is set (about 1–2 minutes). Carefully lift the crepe onto a plate.
Assemble the rolls: place a spoonful of the pork-and-mushroom filling onto each crepe, add a slice of Cha Lua (Vietnamese pork sausage) if using, then roll or fold the crepe to enclose the filling. Repeat until the batter is used.
Plate and garnish: serve the bánh cuốn warm with a side of the dipping sauce and fresh accompaniments — crisp Bean Sprouts, thinly sliced Cucumber, a handful of Cilantro and Mint, and a scattering of Fried Shallots on top for crunch.
To eat: dip each roll into the sauce and enjoy the interplay of silky crepe, savory filling and bright, herbaceous garnishes.
