Tamarind is a rather ugly fruit; in its natural state, the thin-shelled pod resembles old, dust-covered dog droppings. The taste, though, is anything but dry and dusty - it's sour and sweet. It's used as a seasoning in Africa, Southeast Asia and India, where it's usually available fresh, as a paste and as a thick, dark syrup.
When buying fresh tamarind, look for pods that are swollen and full, rather than thin and flat, as this means they're ripe and therefore sweeter and less acidic. For tamarind paste, cut or break off the appropriate amount and stir it into hot water to dissolve it, then strain it to remove the fibres and seeds. Tamarind is also made into a chewy candy and, when diluted with cold water, makes a refreshing drink.
Tamarind is used in the traditional version of pad Thai, where its sour flavour is balanced with palm sugar (cheaper restaurants rely primarily on tomato ketchup as the main seasoning). In Malaysia, any dish with the word "assam" in it is sure to include tamarind. One of my favourite Malaysian dishes is assam laksa, which isn't easy to make. It requires fish stock; a spice paste made with chillies, shallots and belacan (fermented shrimp paste); tamarind water; an oily fresh fish such as mackerel; and garnishes that include fresh herbs, chillies, fresh pineapple and dark, pungent shrimp paste.