Have you ever eaten Rawon? This Indonesian cuisine has a distinctive seasoning , called kluwek. Kluwek (Pangium edule) on rawon used as a spice and natural coloring of black on the gravy. Besides being used in rawon , kluwek also used on Makassar (Sulawesi) dish, called Sop Konro, and Brongkos, other Indonesian vegetable.
The tree of Pangium edule requires many years to mature and produce fruit, therefore kluwek most often harvested from wild trees, as it’s less economical to be cultivated. Fresh fruit and seed of kluwek containing hydrogen cyanide and toxic if consumed without prior preparation. The seeds must first be boiled and then buried in ash, banana leaves on the ground for forty days, during this time, they will turn from creamy white to dark brown or black. This process occurs because the hydrogen cyanide released during boiling and fermentationing. The edible part of this plant is also an excellent source of vitamin C and iron.