VIETNAMESE CHICKEN NOODLE SOUP

Steps:

• Chicken stock:
• Bring chicken, onion, carrots, celery, and 5 quarts water to a boil in a large heavy pot. Reduce heat and simmer, skimming surface occasionally, until broth is flavorful and reduced by one-fourth, about 2 hours.
• Strain stock through a fine-mesh sieve into a large bowl; discard solids. (You should have about 4 quarts). Let cool, then cover and chill.
• DO AHEAD: Stock can be made 5 days ahead. Let cool, then cover and chill.
• Soup:
• Rub chicken legs with five-spice powder, grated ginger, 1 tablespoon salt, and 1 tablespoon sugar; let sit 15 minutes.
• Meanwhile, heat broiler. Spread out halved ginger and onions on a rimmed baking sheet and broil, turning occasionally, until charred all over, 15-20 minutes. Add lemongrass, cardamom, star anise, cinnamon, and cloves to onions and ginger and broil until lightly charred and fragrant, about 1 minute.
• Transfer onion mixture to a large heavy pot. Add chicken stock and fish sauce and bring to a boil. Add seasoned chicken, reduce heat, and simmer until chicken is just cooked through, 20-25 minutes.
• Using tongs, transfer chicken to a plate. Let cool slightly, then remove skin and bones; discard. Shred meat. Continue to simmer broth until it reduces slightly and flavors concentrate, 50-60 minutes. Season with more salt and/or sugar, if desired. Strain into a large bowl or clean pot.
• Cook noodles according to package directions. Using tongs or a spider, transfer noodles to a colander and run under cold water to stop cooking; set aside. (Keep pot of boiling water handy for reheating noodles.)
• Just before serving, return noodle cooking water to a boil. Place noodles in a fine-mesh sieve and lower into hot water to reheat, 30 seconds.
• Divide noodles among warm bowls and add shredded chicken and bean sprouts. Ladle hot broth over, dividing evenly. Serve with Spicy Pickled Shallots, herbs, and lime wedges for squeezing over.
• DO AHEAD: Seasoned chicken broth can be made 2 days ahead. Let cool, then cover and chill. Bring to a boil before serving.