I didn't have a lot of the ingredients that I needed to make my Thai soup, so I improvised a bit. The result was ok, but not my favorite. I used lime zest and lime juice instead of kaffir lime leaves, and I didn't have any fish sauce or chili peppers.
The recipe I have included is not the one I used tonight, but it was one I made a long time ago, when I took a brief Thai cooking course. It is definitely worth it to try and procure all the ingredients listed below. You may have to go to your nearest China town to find some of them.
Four years ago I was in Thailand for 10 days, as part of my back packing around the world. I was in Bangkok for the first three days and then I went north to Chang Mai. After "trekking" through the jungle for three days (there wasn't that much trekking, and if you consider the fact that there was no wild life in this said jungle, it was more like walking in the woods for three days) I decided to take it easy and took a Thai cooking course.
It was so much fun and it only cost about 60$ at the time, which is pretty good considering we just ate and cooked all day. We even went to a market to pick out our ingredients before we cooked.
I learned how to make green and red curry paste using a mortar and pestle, and as rewarding as it was to make it myself, my arm was utterly killing me by the end of it. Usually I am a do-it-yourself kind of girl, but in this case I would much rather buy the convenient curry paste in the package, then pound chilies for 20 minutes.
Tom Kaa Kai, Chicken in Coconut milk soup
Source: Smart Cook, Thai Cookery School
200g boneless chicken breast, sliced 1 inch thick
1 1/2 cups coconut milk
1/2 cup of coconut cream
20 g of large onion, cut into quarters
3-4 thinly sliced Thai ginger
20g sliced lemon grass
1-2 kaffir lime leaves
3-5 fresh chilies
50g of oyster mushrooms
1 Tbsp fish sauce
1 Tbsp chopped spring onion and coriander
1 Tbsp of sugar
1 tomato, cut into quarters
2 Tbsp lemon juice
Heat coconut milk gently over medium heat in a sauce pan. Add the lemon grass, Thai ginger, kaffir lime leaves and chilies and bring to a boil for 3 minutes and add chicken and wait one minute and stir.
Add large onion and mushrooms and tomatoes one minute later. Add fish sauce, lemon juice, and sugar. Add the coconut cream and stir for one minute and than turn off the heat.
Top with chopped spring onions and cilantro.