Unripe Sampalok (Tamarind) Fruits

Unripe fruits of the sampalok or tamarind tree, scientifically known as Tamarindus indica,  are typically used as souring agent for the soup dish sinigang. The fruits are crushed by hand or by mortar-and-pestle, then dropped into the boiling broth. Here is a picture of the sampalok fruits a family friend gave us: