In a large bowl, dissolve the rice flour, turmeric powder, and salt in water.
Add the beer, coconut milk, and green onions. Mix well and let the batter rest for 30 minutes.
In a bowl, mix the filling ingredients, let rest for 10 minutes
Heat a non-stick pan (20 cm in diameter) over high heat. Add oil. Add the pork. Wait a few minutes until it's well browned, then mix and break up the ground meat. Wait again, and repeat until you get nice small pieces of well-browned ground meat. Set aside
Reheat the pan over medium-high heat. Scoop a ladle of batter and tilt the pan in a circular motion to spread the batter evenly. Cover and cook for 1 minute.
Uncover and add a handful of bean sprouts, then cover again and fry for an additional minute.
Uncover, add a few spoonfuls of the filling.
Fold the crepe in half. Fry for another minute and transfer to a plate. Repeat until the batter is used up. If you can use 2-3 pans at the same time, it's faster.
To serve, use scissors to cut the crepe in half. Take a large lettuce or mustard leaf (rau cai) or softened rice paper, place some herbs and half a crepe on it. Roll, dip in the fish sauce, and enjoy.
Notes
Rice flour or wheat flour?I decided to keep the traditional method for making bánh xèo, using only rice flour. But if you prefer, you can certainly replace this rice flour with ordinary wheat flour. Why consider wheat flour? Because it makes the crepes crispier and gives them a nice golden color when cooked. And if you make the batter in advance, it will even hold up better with wheat flour when reheated. The thickness of the batterMake sure the batter is not too thick. Whether you've weighed the flour or not, check its consistency. The batter should be fluid and not have the consistency of a thick fritter batter. If it's too thick, thin it by adding a tablespoon of water, mix, then test. Repeat if necessary.