Start by making the peanut dipping sauce. Combine the peanut butter and hot water until smooth. Then stir in the rest of the sauce ingredients. Set aside.
Toss the shrimp with salt and pepper to taste. Heat a cast iron skillet over high heat until smoking. Sear the shrimp, tossing once or twice, until they are pink and just cooked through, about 2 minutes. Set aside.
Whisk together the garlic, sugar, fish sauce, and lime juice in a large bowl. Toss in the bean sprouts, carrot, and scallions, and set aside.
Boil the rice noodles according to the package instructions. Drain thoroughly and rinse under cold water. Set aside.
Now you are ready to assemble. Fill a pie plate halfway with tepid water. Immerse a wrapper into the water, and hold it there for about 5 seconds. It will still be quite stiff, but will soften very quickly as you assemble the rolls.
After 5 seconds has elapsed, immediately pull the wrapper out of the water and lay it on a clean work surface. Start by laying down a few pieces of shrimp horizontally across the middle of the wrapper. Add some of your rice noodles, the marinated vegetables, and a few leaves of each of the three herbs (basil, cilantro, and mint)
Fold the sides of the wrapper over the filling, and then roll from bottom to top into a cigar. Place on a serving plate. Continue until all the rolls are assembled. Serve with peanut sauce!