Tamarind is a leguminous tree bearing edible fruit that is indigenous to tropical Africa.
The genus Tamarindus is monotypic, meaning that it contains only this species. (wiki)
Tamarind is used in Durban Fish & Seafood Curries to give it that trademark sour twang.
Soak the Tamarind in hot water to 15 minutes and then strain the water into your dish.
Here are some Fish & Seafood Recipes.