Ingredients

1. 1 1/2 cups canned unsweetened coconut milk
2. 1/2 cup thinly sliced shallots
3. 2 serrano or Thai chiles, cut in half lengthwise
4. 1/8 teaspoon turmeric
5. 14 curry leaves
6. Salt
7. Water
8. 8 ounces rice sticks (see Note)
9. 1 tablespoon vegetable oil
10. 1/4 teaspoon mustard seeds
11. 1 dried red chile
12. 1 tablespoon fresh lime juice

Directions

1. In a medium saucepan, combine 1 cup of the coconut milk with the shallots, serrano chiles and turmeric. Add 8 of the curry leaves, 1/2 teaspoon of salt and 1 cup of water and simmer over moderate heat until thick and the shallots are softened, about 15 minutes. Add the remaining 1/2 cup of coconut milk and bring just to a simmer. Cover and remove from the heat.
2. Meanwhile, bring a large pot of water to a boil. Add the rice sticks and 1/2 teaspoon of salt, return to a boil and cook, stirring occasionally, until al dente, about 5 minutes. Drain well and divide the noodles among 4 bowls. 
3. In a small skillet, combine the oil, mustard seeds, dried red chile and the remaining 6 curry leaves. Cover and cook over moderately high heat until the mustard seeds pop. Stir the spice mixture into the sauce along with the lime juice and a generous pinch of salt. Spoon the sauce over the warm rice noodles and serve immediately. 
4.  

Notes

Rice sticks are available at Asian groceries and large supermarkets.