Soak the dried mung bean noodles in warm water (submerge them completely) for 30 minutes. Drain thoroughly, and cut into ¼ inch pieces.
In a large bowl, combine the noodles, ground pork, grated carrot, chopped wood ear mushrooms, shallots, garlic, ginger egg white, fish sauce, vegetable oil, salt, white pepper, and 1 teaspoon sugar. Mix until everything is uniformly combined.
Wrap the spring rolls:
In a large, shallow bowl or deep plate, dissolve the remaining 2 teaspoons sugar in 1 cup warm water. Sugar is optional but does help the spring rolls to brown when frying.
To wrap each roll, place a rice paper wrapper into the sugar water for about 5-10 seconds, making sure it is completely submerged. Remove it from the water. It will still be quite firm, but it will soften quickly!
Place about 40g of filling in a log shape on one side of the wrapper. Begin tightly folding the wrapper over the filling (no air bubbles!), and roll the spring roll forward 1 complete revolution. Lightly press down on each end of the filling to flatten the rice paper and push the filling together to eliminate any air bubbles.
Fold one side of the wrapper towards the middle of the spring roll. Repeat with the other side. Roll the spring roll forward while tucking in the front to prevent air pockets. The rice paper wrapper will stick to itself. It doesn’t require anything additional to seal. Place the rolls on a plate or sheet pan lined with a clean, dry kitchen towel or parchment paper.
Once wrapped, transfer the spring rolls to the refrigerator and chill for at least 1 hour, so they can dry out and firm up. This step helps minimize the wrapper bubbling when frying (though bubbling is normal). Take them out of the refrigerator 15 minutes before frying.
Double-fry the spring rolls:
Heat about 3 cups of canola or vegetable oil in a medium pot to 335°F/170°C (the oil level should be a little over halfway up the sides). Fry the spring rolls in small batches—about three at a time. Make sure they do not touch just after they are placed in the oil as the skins will be sticky until a crust forms. Cook each batch for 5 to 6 minutes, or until light golden brown. (Frying them in small batches prevents them from sticking to each other.)
Use a metal slotted spoon to pull them out of the oil. Drain on a rack, and continue frying. Maintain the correct oil temperature by periodically adjusting your heat.
When ready to serve, refry the spring rolls (yes, they need to be fried twice) at 350°F/175°C for 1 ½ to 2 minutes to make them nice and crispy. Double-frying is important! Serve with fresh lettuce, cilantro, Thai basil, mint and nuoc cham for dipping.
Note: Recipe makes 20 spring rolls, 2 spring rolls per serving.You’ll have about 800g of filling total, so each of your 20 spring rolls should have about 40g filling.