This noodle soup is easy to prepare. Most versions contain shallot, garlic, and chicken giblets, but our family enjoys a simpler preparation that focuses on just a few ingredients, most of which go into the hot stock moments before serving and are then ladled directly into the waiting bowls, with no fancy assembly required. For a nice lunch, present large servings of this soup with a special-event salad. Or, offer it in smaller portions for an elegant beginning to a celebratory meal. This recipe is easily halved.
2. Add the fish sauce and rock sugar to the stock and then bring it to a boil over medium-high heat. Taste and add salt, if necessary. Add the chicken, mushrooms, and noodles. As soon as the soup returns to a boil, remove from the heat. The noodles will have become clear and plump. Taste once more to check the seasoning and adjust with fish sauce or salt.
3. Ladle into soup bowls. Because the noodles are slippery, hold a ladle in one hand to scoop up some soup and chopsticks in the other hand to move noodles into the ladle. Garnish with a sprinkle of the Vietnamese coriander and lots of pepper. Serve immediately. Pass the chiles at the table.
Simple table salt can be transformative on food -- imagine unsalted potato chips or french fries. Paul Breslin, a professor who researches taste perception, explains how salt affects the taste of food.