Here's how Dale makes Tom Kha Kai
(Coconut Milk Chicken Soup)

3 1/2 cups coconut milk
1 lb skinned, boned chicken, cut in small pieces (sometimes I bake and shred chicken)
1/2 lb mushrooms (fresh or dried and/or straw)
1 oz fresh galangal, sliced (I have to use dried; soak in 1/2cup of hot water 30 min 1st) *
1 oz lemon grass cut into 1" lengths (pound first if you want more flavor) *
4-5 kaffir lime leaves, torn in half (or use a knife and make slits in the leaves) *
2-3 fresh chillies, halved (or slice thin; I use 5-6 chiles) *
1/3 cup lime juice
3 tbsp fish sauce (I like Squid brand) *
3 tsp sugar
1 tsp salt (I don't add salt because the fish sauce is so salty)
2 tbsp chopped corainder greens (cilantro)
1 tbsp roasted chilli sauce (nam phrik phao)
           (I don't have this so I add some crushed red pepper just before serving)

Put coconut milk into a medium-sized pot (I use a wok), add 1 cup of water and bring to a boil over medium heat.

Reduce heat, add the galangal, lemon grass, kaffir lime leaves and cook for a few more minutes, stirring occasionally.

Next, add the chicken, (salt), fish sauce, sugar, and lime juice; cook until the chicken is done. (If chicken is baked 1st, this doesn't take long.)

Then add the mushrooms and remove from heat.

To serve: Put 1 tbsp of roasted chilli sauce in the bottom of a large serving bowl
(this is where a I add the crushed red pepper).

Pour in the boiling soup. Serves four.

-- from THE ELEGANT TASTE OF THAILAND, Kongpan & Srisawat (1989).
                          (Get the book!)

Says it serves four, but doesn't say four what!
You can use chicken breasts, but Steve likes dark meat.
He thinks it's best when both white and dark meat are used.

* You may have to get this at an Oriental grocery store