Bring a large pot of water to a boil. Meanwhile, combine the sugar and 2 tablespoons hot water in a large bowl and stir until dissolved. Stir in the lime juice, garlic, chile and fish sauce; transfer 2 tablespoons of the dressing to a medium bowl and whisk in the vegetable oil. Add the shrimp and toss to coat; set aside.
Add the rice noodles to the boiling water and cook as the label directs; drain, rinse with cold water and shake off the excess liquid. Add the noodles to the bowl with the remaining dressing; add the lettuce, carrots, cucumber and herbs and toss to coat.
Heat a grill pan over medium-high heat. Grill the shrimp until charred and cooked through, 2 to 3 minutes per side. Arrange over the noodles; serve with lime wedges.
Courtesy of Food Network Magazine, Photograph by Justin Walker