spring roll wrappers (we used rather large egg roll wrappers, which is why they bubbled, I think)
1 beaten egg (for wrapping)
full 48-oz bottle vegetable oil
sweet chili sauce (for dipping)
Follow package directions for stir-frying glass noodles in a wok (softening in water first if needed) until they are just barely soft enough to eat, the remove from wok and set aside.
Heat a splash of vegetable oil in the wok and stir fry garlic until golden, then add the mushrooms and carrots. Cook until softened. Add fish sauce, oyster sauce and sugar, stirring until coated, and softened noodles. Add bean sprouts and spring onions. Stir fry until the fresh vegetables are just cooked through. Set aside mixture.
Lay out one spring roll wrapper on a plate, rotating it so the point is toward you and the wrapper is making a diamond shape, not a square. Brush edges of wrapper with beaten egg. Add a heaping tablespoon of filling (less if you’re using small spring roll wrappers) and turn up bottom corner of the diamond wrapper to cover the filling. (See image above.) Trying to avoid air pockets, fold in the two sides and roll up like a tight burrito with a triangle flap on top. The egg wash will hold it closed.
Once you have them folded, fill and 8 qt pot with at least 3-4 inches of vegetable oil for deep frying. Heat oil to 375 F. (When the oil seems hot, test by dropping a small piece of spring roll wrapper into the oil. If it floats and sizzles immediately, the oil is ready. Deep fry 3-4 spring rolls at a time—do not crowd the pot. Flip them (or rotate and hold with a metal spoon) once one side is brown. Remove from pot to a paper towel to drain.
The spring rolls can be placed in the oven on a cookie sheet at low heat (around 200) to keep them warm while a second or third batch is frying.