The nuoc cham is spicy, sweet, sour, and somewhat funky; when you add coconut milk, some of the fire is toned out and replaced with a rich creaminess. Since the nuoc cham contains a fair amount of fish sauce, it makes a sensible companion to seafood. Here, we've used shrimp, though flaked poached fish would be welcome, too. The fast-to-cook rice noodles will loop around whatever protein you've chosen, catching the sauce and hiding kernels of corn and little sweet peas.
In a jar, mix the sugar, fish sauce, lime zest, and lime juice with a fork or whisk until the sugar is completely dissolved. Add the garlic and chilies and a few grinds of black pepper, and let everything hang out for around 30 minutes. Taste and adjust sugar and lime juice. This will keep in an airtight jar in the fridge for up to 1 week.
Whisk in the coconut milk, then drizzle in the oil, whisking to emulsify. Taste and adjust.
For the salad:
Place the rice noodles, corn, and peas in a large bowl. Bring a kettle of water to a boil, then pour the hot water over the rice noodles. Let this sit, stirring occasionally, for 10 to 15 minutes, until the noodles are tender. Drain, rinse with cold water, and drain well.
Mix the noodles and vegetables with the coconut nuoc cham. Mix in the shrimp, then top with the bean sprouts, wasabi peas, and fresh herbs. Serve with lime wedges.