Tamarind

Tamarind is a tropical fruit used primarily as a souring agent in South Asian, Southeast Asian and Caribbean cooking. It is sold as a compressed block, a paste or a concentrate. The block form requires soaking in warm water, then pressing through a sieve to extract the pulp. Its flavour is deeply sour with a warm, almost toffee-like sweetness underneath, quite different from vinegar or citrus. In a complex sauce such as Luke's brown sauce it provides background acidity with length. It is also the key souring component in Worcestershire sauce and many commercial brown sauces.