Ingredients:
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1 lb.          medium shrimp
2 sticks      fresh or 2 tablespoon. dried lemongrass
4               fresh or dried kaffir lime leaves or 1 tblsp finely grated lemon zest
1 1/2 qt     chicken stock
1 tblsp       fish sauce or salt to taste
3 tblsp       fresh lime juice or to taste
1 tsp         Thai chili paste(nam prik pow) or substitute 1/4 tsp cayenne, 1/4 tsp sugar, 1/2 tsp oil
15 oz.       can straw mushrooms or 12 med. fresh mushrooms
3              fresh hot green chilies
3 tblsp      cilantro

Instructions:
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Wash, peel, de-vein shrimp.  Save shells.  Wash shrimp again, drain, pat
dry, cover and refrigerate.  If using fresh lemongrass, cut each stick
into three 2 inch pieces--starting from rounded bottom end.  Discard
straw-like top.  Lightly crush the 6 pieces.
 
In a pan, combine lemongrass, lime leaves, stock, and shrimp shells.
Bring to boil.  Lower heat and simmer gently for 20 minutes.  Strain
stock, then add fish sauce, lime juice, and chili paste.  Adjust fish
sauce and lime juice to taste.  *Add more chili paste for more heat.
 
Drain straw mushrooms and add to stock.  (If using fresh mushrooms,
quarter them and drop in lightly salted boiling water.  Boil 1 minute.
Drain and add to stock.) **The soup can be prepared to this point
several hours ahead of time and stored in the refrigerator.**
 
Prepare garnish shortly before serving.  Cut green chilies into fine
rounds.  Wash and dry cilantro.  Just before serving, heat the soup,
when it begins to boil, drop in peeled shrimp.  Cook on medium heat for
2 minutes or just until shrimp turn opaque.  Garnish with chilies and
cilantro leaves.  Serve hot.