Bring a medium saucepan of water to a boil over high heat. Add the shrimp and cook until bright pink and just opaque, about 1 1/2 minutes. Drain in a colander and run under cold water until cool. Pat the shrimp dry with paper towels and place on a cutting board.
Holding your knife parallel to the cutting board, halve each shrimp horizontally.
Place in a medium bowl, cover with plastic wrap, and refrigerate.
Cook the rice noodles according to the package directions. Drain and set aside.
Place all of the ingredients in separate containers and arrange them in the following order around a work surface: rice paper wrappers, shrimp, rice noodles, bean sprouts, mint, basil, cilantro, serrano (if using), cucumber, scallions, and lettuce.
Place a clean, damp kitchen towel on a work surface. Fill a medium frying pan or wide, shallow dish large enough to hold the rice paper wrappers with hot tap water. Working with 1 wrapper at a time, completely submerge the wrapper until it is soft and pliable,