A popular Thai dish, closer to a curry than a soup. It is usually served with rice.
Bring the lemongrass, ginger, lime leaves, and broth to a boil in a large saucepan. Reduce heat and simmer until flavors are melted.
Strain the mixture, discarding solids
Combine liquid and chicken to a saucepan and bring to a boil. Reduce heat, add mushrooms, and simmer, skimming occasionally, until chicken is cooked through and mushrooms are tender.
Mix in coconut milk, nam pla, and sugar. Serve, garnishing with chile oil, cilantro, and lime wedges.