Step 1Place the lime juice, rice vinegar, sugar and water in a bowl and stir to dissolve. Add the fish sauce, starting with 4 tablespoons. Taste and adjust the flavors. Aim for a balance of tart, sweet and salty. Add the garlic and chiles and place in a serving bowl. Makes about 1 1/3 cups.
Step 1Place the raw rice in a bowl and add enough water to cover by 1 inch. Let soak for 3 to 4 hours. Drain.
Step 2Place the soaked rice in a blender with the cooked rice, mung beans, salt, turmeric, coconut milk and water. Blend until very smooth and lemony yellow, about 3 minutes.
Step 3Pour the batter through a fine mesh strainer into a bowl and discard the solids. Stir in the green onion. Set aside. As the batter sits, it will thicken to a consistency like that of heavy cream. Makes 3 cups of batter.
Step 1For each crepe, heat 2 to 3 teaspoons oil in a 10-inch nonstick skillet over medium-high heat. When the oil is hot enough to gently sizzle a slice of onion on contact, add one-fourth cup onion, one-fourth cup pork, one-fourth cup straw mushrooms and 4 medium or 6 small shrimp. Saute quickly, breaking up the meat and letting the ingredients sear and aromatize, about 1 minute. Visualize a line down the skillet's middle and roughly arrange the ingredients in the two halves. Anything arranged in the middle will make it hard to neatly fold the crepe.
Step 2Give the batter a good stir with the ladle. Pour about one-half cup batter into the skillet, swirling the skillet to cover the bottom; a bit going up the side forms a lovely lacy edge. The batter should dramatically sizzle (making that "xeo" noise!) and bubble. When it settles down, scatter 2 tablespoons mung beans over the crepe surface and place a one-third cup bean sprouts on one side. Turn the heat down to medium-low, cover and cook until the bean sprouts have slightly wilted, about 3 minutes.
Step 3Remove the lid and drizzle about 1 teaspoon oil around the edge of the crepe. Continue cooking, uncovered, to crisp the pancake. After about 3 to 4 minutes, the edges should have pulled away from the skillet and turned golden brown. At this point, use a spatula to check underneath. From the center to the edge, the crepe should gradually go from being soft to crispy. Lower the heat if you need to cook further. When you are satisfied, use a spatula to fold one half over the other. Either lift the crepe with a spatula or slide it onto a serving dish. Repeat the cooking process. If there's leftover batter, make the poor man's crepe without the goodies.
Step 4To eat, tear a piece of lettuce roughly the size of your palm and place a piece of the crepe inside (use kitchen scissors or chopsticks to cut the crepe). Add cucumber slices and a few herb leaves. Use your fingers to bundle it up, then dunk it into the dipping sauce.