I've used two different recipes (from two different books) to make this coconut soup. Here is the easier (by far) of those recipes. It is from "Simply Thai Cooking" by Wandee Young and Byron Ayanoglu.

14 oz skinless, boneless chicken breast
1 stick lemon grass
1 inch galangal root
4 lime leaves (or 1 TBS lime juice)
2 fresh hot chilies
2 cups unsweetened coconut milk
1 cup water
2 TBS lemon juice
1 TBS fish sauce
1/4 tsp sugar
Fresh coriander leaves

Slice chicken into thin (1/4") strips. If you find it difficult to cut thinly through fresh meat, leave it in the freezer for 15-20 minutes to harden slightly and then slice. Reserve.

Smash lemon grass with the flat of a chef's knife once, and then cut it into 1" pieces; slice galangal into thin rounds; tear lime leaves into thirds; cut chilies in half. Reserve all four of these mixed together in a bowl.

Heat coconut milk and water in a saucepan for 2-3 minutes. Don't let it boil. Reduce heat to medium and add reserved lemon grass/galangal/lime leaves/chilies and cook for another 2 minutes, stirring continuously and not letting it boil.

Add chicken strips and cook for 5 minutes, stirring over medium heat, until the chicken is cooked (don't overcook and lower heat if it threatens to boil).

Add lemon juice (plus lime juice if you haven't been able to find lime leaves), fish sauce and sugar. Stir, and continue cooking for another minute or two. Transfer to a soup tureen and serve immediately, garnishing with fresh coriander leaves.

A little note about this and other soups: lemon grass, galangal root and lime leaves, the trio of flavors that give many Thai soups their distinctive taste are unchewable, but form dictates that they be left in the soup. It is then up to the soup slupers to avoid eating them. Furthermore, though lemon grass is easy to find, galangal root and lime leaves are not so easy. They can be substituted with ginger root and lime juice, respectively.

Thanks Beachlily.

Tropicalfreak