Hot-and-Sour Prawn Soup with Lemon Grass

Shell and devein the prawns reserving the shells. Rinse the shells and place them in a large saucepan with the chicken stock. Bruise the lemon grass stalks and add them to the broth along with half of the lime leaves. Bring to a boil then reduce heat to low and simmer gently until the lemon grass changes color and the stock becomes fragrant about 5 minutes. Strain the stock and return to the saucepan. Discard the solids.

Return the stock to a simmer and add the mushrooms and prawns. Cook until the prawns are pink. Stir in the fish sauce lime juice 2 tablespoons green onion cilantro red chilies and remaining lime leaves. Taste and adjust seasoning if necessary. The soup should be sour salty spicy and hot. Garnish with remaining green onions.