Thai Hot and Sour Shrimp Soup
This hearty, flavorful soup is traditionally served alongside main dishes, with plenty of jasmine rice, but it can also be served as a first course.
In a 3- to 4-quart saucepan, combine the broth or water with the fish sauce, chiles, lemongrass, galangal, lime leaves, cilantro root, and sugar, and bring to a vigorous simmer.
Add the mushrooms and shallots, and cook until soft, 2 to 5 minutes.
Add the shrimp and lime juice. Season to taste with sugar and chiles. (The soup should be hot, sour, and salty. Sugar is to balance the other flavors; the soup should not be sweet.) Cook until the shrimp are just pink, 2 to 3 minutes.
Serve topped with the sawtooth coriander and scallions.