Kao soi (sometimes spelled Khao soi) is a curried noodle and chicken soup from Chiang Mai, Thailand. When I went to Thailand a few years ago as an undergraduate student to do water quality research, I had absolutely no idea what to expect. Aside from the amazing research experience, I also met wonderful people and fell in love with the cuisine and culture. My absolute favorite new food was Kao soi. We would often eat it for lunch just after doing our morning field work in the rice paddies and before going to the lab. The first time I ate this dish, I was blown away. It seemed so simple - a big bowl of curried broth and noodles along with a chicken drumstick, but the flavors were anything but. And, as with much Thai food, there's a big plate of adornments to add on top: cilantro, thinly sliced onions, lime wedges, chili sauce, and soy bean paste.
A couple of years ago, my Thai friend came here to do a semester exchange, so I got to see her a lot. She brought along with her some special Thai yellow curry so that she could try to teach me to make Kao soi at home. Luckily, we have a substantial Asian population in our area, and lots of little Asian markets. So, after we visited a few of these, we gathered up suitable ingredients to attempt to make this dish. It was wonderful! While we were making it, I was making some mental notes and she was writing down a list of ingredients. Since then, I have not tried to replicate Kao soi on my own. Mainly because I felt like I'd be disappointed if I didn't get it "right" and also because I couldn't find the special yellow curry paste.
Recently, I received a copy of the cookbook Thai Food for my birthday. In it, there is a recipe for Kao soi. So I decided to give it a try again, this time all on my own. I went to an Asian grocery and asked if they had a Thai yellow curry paste, and they did - the writing was all in Thai and I never would have known that's what it was... I also found a package of fresh Asian style noodles. With those in hand, the rest of the ingredients are easily available at most large grocery stores. You can find Thai Kitchen brand red curry paste and it's actually pretty good. While I have made green curry paste before, I have not attempted red or yellow - it can be hard because finding galangal and keffir lime can be difficult, and the store-bought pastes already contain these ingredients. The result was a success - the smell made me so happy and the taste made me quite ecstatic. It was very close to my memory of eating Kao soi from a small noodle shop in Chaing Mai.
On the the recipe... This is a combination of the cookbook recipe, my friend's recipe, and my memory. Many of the measurements are not exact because of the heat/spice levels -- taste and adjust to your liking. This recipe will make about four servings.