Tom kha kai or Tom kha gai (Thai: ต้มข่าไก่, RTGS: tom kha kai, IPA: [tôm kʰàː kàj]; Lao: ຕົ້ມຂ່າໄກ່, tom kha kai), literally "chicken galangal soup") is a spicy hot soup in Lao cuisine and Thai cuisine. This soup is made with coconut milk, galangal, lemon grass, kaffir lime leaves, and chicken, and often contains straw, shiitake, or other mushrooms, as well as coriander leaves(see below). The fried chilies add a smoky flavor as well as texture, color and heat, but not so much that it overwhelms the soup. The key is to get a taste balance between the spices. Thai-style tom kha gai does not use dill weed, whereas Lao-style tom kha gai usually contains "phak si" (dill weed), which is a common herb used in Lao cuisine. The Thais' answer to dill weed (known in Thailand as "phak chi Lao", since it is known locally as a Lao herb) in Tom kha is coriander or cilantro ("phak chi" in Thai).
There are other versions of this soup made with seafood (tom kha thale), mushrooms (tom kha het), pork (tom kha mu) and tofu (tom kha taohu).