Tom Yum Goong
Lemon Grass-Shrimp Soup
Source:  Simply Thai Cooking, p. 58

4 cups of water
1 stick lemon grass
4 lime leaves or 2 tBs/25mL lime juice (I use lime juice)
1 inch galangal root or ginger root (I use ginger)
2 fresh hot chilies (I rarely put them)
3 tBs fish sauce (I occasionally replace them with soy sauce,
  preferably something like Kikkoman, or another japanese brand - 
  they tend to be of better quality)
1 tsp sugar
1.5 tsp chili paste (buy in any chinese store, I think I managed to find some in Consum)
2 oz button mushrooms, quartered
16 large shrimps, shelled and deveined (300g, can be replaced with white fish)
3 tBs lime juice (this in addition to above)
fresh coriander leaves

1. Heat 4 cups/1 Liter of water in a soup pot to boiling.

2. Smash the lemon grass with the flat of a chef's knife once,
 and then cut into 1-inch/2.5 cm pieces; tear the lime leaves into
 thirds; and slice the galangal into thin rounds. Reserve all three
 of these ingredients together.

3. Crush the fresh chilies and cut in half. Reserve separately.

4. When the water has boiled,
  - add the reserved lemon grass/galangal/lime leaves (UNLESS using lime juice).
  o boil for 1 minute
  - add fish sauce, sugar, chili paste
  o boil for another 2 minutes
  - add mushrooms
  o boil for 2 minutes
  - add shrimps and lime juice (3 tBs/45 mL plush the other 2 tBs/ 25 mL if you
    haven't used the lime leaves)
  o LOWER the heat to medium high
  o cook for 2 minutes, just until shrimps have turned white and springy.
  Transfer to a soup tureen, decorate with fresh coriander leaves and serve
  immediately. (Galina's note: don't skimp on coriander)