The word kaeng (pronounced 'gang' means two different things: one is a stew like dish, usually a curry or a chili, and the other is a soup. In Thai these are different words, and it is the bane of having to transliterate them into Latin characters that reduces them to sameness. Some writers spell the curry word kaeng and the soup-word gaeng, others try to reflect the slightly more aspirated sound of the soup by spelling it 'khaeng'. Whatever: this uses the light semi-transparent vermicelli style noodles known as wunsen in Thai.
You should also note that there are two types of soup in Thai cuisine: one type the Toms (tom kha kai, tom yam etc) are designed to be eaten with a meal. The other style, known collectively as kuiteao nam (pronounced roughly "gw-eye-tee-ow nam") or "wet noodle dishes", are a popular form of fast food in Thailand. They form a full meal and are regularly eaten for everything from breakfast to early dinner, costing only about 50 cents for a large helping in stalls and shops across Thailand (perhaps a bit more in Bangkok itself). This kaeng djuut is a kuiteao nam style "luncheon" dish. (In parallel with the kuiteao nam dishes there is a wide range of kuiteao haeng (dry noodles) dishes)
The recipe calls for a small amount of tangchi (preserved Chinese radish), which can be obtained from Chinese stores. If you can't get it feel free to leave it out entirely.
You will also need a chicken stock: in Thailand they eat all of the chicken except the feathers and the beak - and yes they do eat the feet. However the bones are left over, and stock is made from the bones. Take about a kilogram of bones, and break them roughly with a large mallet or the pestle of your mortar and pestle (also widely used by Thai chefs to keep their husband's in line - made of granite it makes a handy weapon :-) To each kilogram of bones add about a tablespoon of garlic, a tablespoon of ginger and a tablespoon of coarsely chopped coriander/cilantro. Cover with water and boil up your stock. Filter well, cool and then skim off any fat that accumulates on the surface if you want a low fat variant.
Soak the wunsen in water at room temperature for about 10 minutes to soften it, then drain it thoroughly.
Heat a little oil in a wok and stir fry the onion, garlic and ginger briefly.
In a saucepan add the tangchi to a pint of stock and bring it to a gentle boil.
Briefly stir fry the chicken to seal it, then transfer the chicken and onion, garlic and ginger to the stock, add the remaining ingredients, except the garnish and the wunsen, and simmer until the chicken is just about cooked through. Increase the heat to bring the pan to a rolling boil, add the noodles, and immediately turn the heat off.
Pour the soup into a serving tureen, sprinkle with the garnish, and deliver to the diners. Each diner should have a bowl with some fresh boiled rice. Traditionally each takes a spoon of soup from the communal serving bowl, picks up a little rice and then eats it. You may prefer to ladle portions of soup over the diner's rice bowls.
In my opinion the quantities above make about enough for 4 people for a light lunch. Scale according to the number of diners and how hungry they are.
Normal table condiments would be chilies in fish sauce (prik nam pla), chili powder (prik phom) and sugar, you might want to add dark sweet soy as well.
Recipe By: Muoi Khuntilanont