In a large stockpot, bring 2 quarts of water to a boil over high heat. Add the noodles and swirl in the hot water. Cook for 1 minute or until just tender. Drain thoroughly in a colander and rinse under cold water to prevent the noodles from sticking together. Transfer the noodles to a large bowl and chill.
Bring 1 quart of water to a simmer in the bottom of a steamer. Arrange the shrimp on the steaming rack. Place a rack over the simmering water, cover, and steam just until the shrimp are pink and cooked through, about 2 minutes.
Step three: Prepare the dressing
In a medium bowl, soak the red chilies in the lime juice for 2 to 3 minutes. Add the remaining dressing ingredients and stir to dissolve the sugar.
Pour the dressing over the noodles, add the green papaya, cucumber, herbs, and scallions and toss. Add the shrimp and top with chopped peanuts, serve at room temperature.