Batwan is most commonly used as a souring agent in cuisine in Negros, whereas other places in the Philipines are using kamias or Tamarin.
Batwan is a hard, green fruit with a tomato-like shape. It grows wild in the rainforests of Negros. The unripe fruit is cooked as a souring agent with fish, pork, and in soups, such as sinigang and tinola soups. The ripe fruits can be eaten, but are very acidic.