I'm thai and want to change some ingredients in the recipe. Well, I will tell you how to cook Tom Ka Gai. Firstly, you got to cook pieces of chicken breast in coconut milk--you can add some water--depends on how thick you like. Secondly, put 3-5 pieces of lemon grass (2 inches each), 3-5 pieces of galanga (0.5 centimeters thick), 3-5 kaffir lime leaves (we called it bai-ma-grood), lemon or lime juice, fish sauce, crushed fresh chilli, coasly chopped cilantro, mushroom or cabbage. The taste will be a bit sour, salty and spicy. You can buy all ingredients in asian food shop. Don't put ginger because "Ka" in thai means galanga. Those two are look alike, but their smell are totally different. We eat Tom Ka Gai with rice and when you eat it don't eat lemongrass, kaffir lime leaves and galanga. We put it for smell not eat.