- 1/3 cup Asian fish sauce (nuoc mam; see Notes)
- 2 scallions, very finely chopped (white and green parts)
- 1½ tablespoons freshly squeezed lime juice
- ½ tablespoon sugar
- Pinch of red chile flakes
- 24 medium shrimp, about 1 pound, peeled, deveined, and cut in half lengthwise
- 4 ounces dried rice-stick vermicelli noodles
- 4 small Bibb or butter lettuce leaves, ribs removed, cut in half lengthwise
- About ½ cup fresh mint leaves, coarsely chopped
- About ½ cup fresh cilantro leaves, coarsely chopped
- 4 scallions, sliced lengthwise and then into 2-inch pieces (white and green parts)
- 8 to 10 rice paper rounds, about 8½ inches in diameter
- Make the sauce: In a small bowl, mix together the fish sauce, scallions, lime juice, sugar, and chile flakes. Taste for seasoning; it should be slightly spicy. Cover and refrigerate for at least 1 hour or overnight.
- Make the rolls: Bring a medium pot of water to a boil over high heat. Add the shrimp, remove the pot from the heat, cover, and let sit for about 3 minutes. The shrimp should be pink and curled at the edges. Drain and let cool.
- Bring another pot of water to a boil. Add the rice noodles and cook for about 4 minutes, or until softened. Drain.
- Fill a large bowl with warm (not hot) water. Line up the shrimp, noodles, lettuce, mint, cilantro, and scallions so you have all your filling ingredients ready for assembling the spring rolls.
- Place the rice paper rounds in the bowl of warm water, one at a time, for 1 or 2 minutes, or until soft and pliable. Drain on a kitchen towel on both sides for several seconds. Place the softened rice paper on a cutting board or clean work surface. Place a piece of the lettuce in the bottom half of the circle. Place a handful (about 2 tablespoons) of the cooked noodles lengthwise on top of the lettuce. Arrange 3 to 4 shrimp pieces on top and scatter over a sprinkle of mint and cilantro. Add 1 to 2 scallion pieces on top. Fold the bottom of the circle up into the roll. Fold the sides into the middle and then, working from the bottom, tightly roll the rice paper circle up into a fat cylinder. Leave seam-side down and repeat with the remaining rice paper circles and ingredients.
- Leave the rolls whole or cut them in half widthwise on the diagonal Place on a large serving platter with the bowl of dipping sauce in the center.