1. Heat the oil in a 6-quart or larger stockpot or soup pot over medium-high heat. Add the shallot, garlic, chopped chiles, ginger, and lemongrass and cook, stirring as needed, for 2 minutes. Add the lime zest, cilantro stems, and chicken broth. Bring to a boil, reduce the heat to low, and simmer for 30 minutes.
2. Strain the broth through a fine-mesh sieve into another pot or bowl, discard the solids, and return the broth to the pot set over medium heat. Stir in the coconut milk, curry paste, lime juice, palm sugar, fish sauce, salt, and sliced chile. Bring the broth to a simmer and cook for 2 minutes. Add the chicken, mushrooms, and snow peas to the pot and cook for 2 minutes longer, or until the chicken is just cooked through. Stir in the green onion and cilantro leaves and remove from the heat. Serve the soup hot, over steamed rice if desired.
Yield: 12 cups, 4 to 6 servings
Note: Also known as nam pla in Thailand, or nuoc nam in Vietnam, fish sauce is a basic ingredient in Southeast Asian cooking. It is used to make marinades and sauces and is often served as a condiment. Fish sauce is derived from fish that has been salted and allowed to ferment. Fish sauce can be found in Asian markets and sometimes in the international aisle of the grocery store. There are many brands of fish sauce, but we prefer Three Crabs, Golden Boy, and Tiparos brands.