Although pad Thai is well known to tourists, and so expected on the menu at every Thai restaurant in the west, the dish is actually not all that common in Thailand. You will find stalls that sell it and Thais do enjoy pad Thai once in a while, but the dish is not nearly as common as many westerners think. It is very much a street food, and perhaps a good example of a strange sort of snobbishness about food. Some things, it seems, just belong on the streets, and are almost never found in restaurants.
The ‘fruit’ of the tamarind tree is in the form of pods three to five inches long and slightly larger around than your finger. A single tree can produce 150 to 250 kilograms of pods each year. When fully ripe, the pods will be light green in color with a slightly velvety skin. They are then allowed to dry in the sun until the shell turns the color of milk chocolate.
Starting in November here in Thailand, the thick brown seed pods of the tamarind tree will begin to appear in the markets. The initial stock usually comes from Petchabun, a province just a few hours' drive south of Chiang Mai, at the edge between northern and central Thailand. These will be packed in bags or even 'gift' boxes. As the season progresses, the many orchards further north around Chiang Mai will ripen and make their way to the markets.