In a medium saucepan
, heat chicken stock, tom yam
paste, lime leaves, lemon grass
, lime juice, fish sauce
, chiles, and sugar. Once it has come to a boil, add mushrooms and simmer
for 2 minutes. Add shrimp and scallions and cook for 2 to 3 minutes allowing the shrimp
to cook but still be tender. Sprinkle with cilantro and serve immediately. Place extra cilantro on the table for people to add more.