Bring a medium saucepan of water to a boil. Add the shrimp and cook until pink, opaque, and curled, about 2 to 3 minutes. Transfer the shrimp to a bowl of ice water for 2 minutes, then drain well. Slice each shrimp in half horizontally to make two thinner pieces.

Cook the rice vermicelli according to the package directions, usually 3 to 5 minutes in hot water. Drain, rinse under cool water, and shake off as much water as possible. Set aside.

For the dipping sauce, whisk the peanut butter, hoisin sauce, lime juice, soy sauce, and 3 tablespoons warm water in a small bowl. Add more warm water, 1 teaspoon at a time, until the sauce is smooth and dip-able. Stir in sambal oelek if using.

Fill a wide, shallow bowl or pie plate with warm water. Dip one rice paper wrapper in the water for 5 to 8 seconds, then place it on a clean, lightly damp work surface. It will continue to soften as you fill it.

Place 3 shrimp halves in a row across the lower third of the wrapper. Add a small handful of lettuce, a small bundle of noodles, carrot, cucumber, mint, and cilantro below the shrimp. Keep the filling compact and leave about 1 1/2 inches (4 cm) clear at the sides.

Fold the bottom of the wrapper over the filling, fold in both sides, then roll upward snugly to enclose the filling. Do not overfill; a firm but gentle roll helps prevent tearing. Repeat with the remaining wrappers and filling.

Serve the rolls right away with the peanut dipping sauce and chopped peanuts, if using.