To prepare the glass noodles, in a bowl, soak glass noodles in warm water for 30 minutes. Drain and cut into 1½-inch lengths.
To make the nuoc cham, in a bowl, dissolve sugar in hot water. Stir in fish sauce, lime juice, garlic, and chili. Set aside.
To make the filling, in a large bowl, combine ground pork, shrimp, glass noodles, wood ear mushrooms, carrot, bean sprouts, shallot, garlic, salt, black pepper, fish sauce, and egg. Mix thoroughly until evenly combined.
To wrap, in a bowl, combine water with rice vinegar (or a tiny pinch of sugar). Lightly brush both sides of each rice paper sheet until just pliable. Place about 2½ tablespoons filling near the bottom edge, fold bottom over filling, fold in sides, and roll tightly to seal.
To fry, in a pan over high heat, heat cooking oil to 325°F (163°C). Fry in batches for about 5 minutes, turning as needed, until lightly golden and internal temperature reaches 160–165°F. During the first minute, keep rolls separated to prevent sticking. Remove and drain.
To double fry, raise oil temperature to 350°F (177°C). Fry for 1–2 minutes until deeply golden and crisp. Drain again before serving.
Serve hot with nuoc cham.