I like Thai iced tea, but I'm usually to cheap to buy it when we eat out.
I finally followed through with my thought of, "gee, perhaps I can make it."
It's super easy to make, just get the right bag of tea. Brew it strong, filter out the tea leaves, sweeten, add cream/half-n-half/condensed milk, and serve.
The trick is (of course) to get the right tea leaves.
Your local asian market will likely have the tea leaves (ours is Rice & Spice). And, the tea leaves are likely to have food-coloring in them. Traditional Thai iced tea comes from certain red tea leaves, which are probably near impossible to get outside of Thailand. So, the tea leaves are colored with food coloring.
Once you've found the tea leaves, you'll have to figure out how you want to sweeten the tea. The guy at the market told me to use sweetened condensed milk. As sweet as that stuff is, by the time you've added enough to make the tea taste appropriately sweet, the drink is too milky. So I add sugar to the tea, and will probably just use half-and-half (or evaporated milk) to give the right amount of creaminess.
Lastly, some of the recipes have you brew the tea for a long time - making it super strong (which is partially why you add cream and lots of ice - to water it down). I've only let mine brew for a couple of minutes, but I'll try the next batch for an hour or so. Regular tea normally gets bitter, but perhaps it'll work out for the Thai iced tea.
FWIW, my tea mix looks remarkably like this one: