In a small bowl, whisk together the peanut butter, hoisin sauce, soy sauce, and rice vinegar. Add warm water a little at a time until you get a smooth, pourable consistency. Top with crushed peanuts if you’re feeling fancy.
You want your fillings ready to go because the rice paper softens fast. Cook the vermicelli noodles according to the package, slice your veggies thin, and arrange everything within arm’s reach.
Fill a shallow dish or large plate with warm water. Quickly dip a sheet of rice paper in the water, about 5 seconds, just enough to soften it slightly. It will continue to soften as you work, so don’t overdo it or it will tear.
Lay the softened wrapper on a clean surface. Place a lettuce leave, folded, in the center, on the edge nearest you. Then pile on cucumber, carrot, herbs, rice noodles. Start to roll the wrapper over the veggies tightly. Before you finish 1 full turn, place the shrimp, red-side down, on the rice paper. Fold the sides of the rice paper over the roll and then continue to roll. This will ensure the shrimp are on the outside of the roll, which looks very nice.
It’s okay if your first few rolls look a little messy. (Honestly, they still taste great.)
Cover finished rolls with a damp paper towel to keep them from drying out while you work.