The Nonya cooking ingredient Buah Keras or Candlenut ( Aleurites moluccana ), is a tree in the family Euphorbiaceae, also known as Candleberry, Indian walnut, Kemiri, Varnish tree or Kuku'i nut tree.
Buah Keras or Candlenut in native range it impossible to establish precisely because of early spread by man, and the tree is now widely distributed in the New and Old World tropics. It grows to a height of 15-25 m, with wide spreading or pendulous branches. The leaves are pale green, simple and ovate, or trilobed or rarely 5-lobed, with an acute apex, 10-20 cm long. The nut is round, 4-6 cm in diameter; the seed inside has a very hard seed coat and a high oil content.
Buah Keras or Candlenut are the seeds found inside the inedible fruits of Aleurites moluccana, a tree that grows throughout tropical regions. They are used, toasted, in Singaporean cooking to help thicken sauces.
Cooking the nuts is essential, as the raw seeds are toxic and have a strong laxative effect. If Buah Keras or Candlenut prove elusive, Brazil or macadamia nuts can be substituted.
Buah Keras or Candlenut have a high oil content and Hawaiians have burned the nuts as candles to give a source of light, hence the name. In Hawaii the oil is also used as a cure for eczema and the seeds are polished and made into jewellery.