About Kluwak nuts
Kluwak nuts come from the kepayang tree (Pangium edule) of Indonesia & Malaysia, a member of the flacourtia family (Flacourtiaceae). The oily, hard-shelled seeds superficially resemble Brazil nuts. Meaty seeds are edible after the poisonous hydrocyanic acid is removed by soaking and boiling them in water. Fermented kluwak nuts become chocolate-brown, greasy and very slippery. Cooked seeds are used in a number of popular Malaysian and Indonesian dishes.
Production of Kluwak nuts
When harvested from the tree, the kluwak is not ready to be used. It needs to be fermented for sometime, due to its poison. The process of fermentation is done after the kluwak is boiled in hot water for sometime and then they are buried in the ground. The humidity of the soil helps the process of fermentation. When ready, the meat of the kluwak will change from white colour into black, and the taste of the good and ready to use should not be bitter.
Buying Kluwak nuts
Kluwak can be easy purchased in most of the Indonesian and Malaysian wet market, where they are sold still in their shells. The colour of the shell is varied from grey to black, but most of the time they are greyish. Normally, it is bought in measures of their weight. However, now we can also buy the dried peeled kluwak without the shell, in a package. This can be bought in the leading supermarkets in the major cities in Indonesia.
Preparing Kluwak nuts
Before using, the kluwak should be taken out from its shell. We need to crush them either with a hammer or the knife holder. Some people will use the traditional indonesian grinder made from stone - which is called as canthuk. When the meat of the kluwak is black there is a possibility that the quality is good. However, before using it we need to taste it. If it is bitter, we can not use it. Sometimes, we will also find the meat white or whitish. It means that the kluwak is not ready to use, and we can not use it.
For the dried kluwak, we need to soak it in a cup of water or lukewarm water for around one night. When the meat is soften, we can use them for cooking.
Cooking Kluwak nuts
In fact kluwak is not the main component of a dish, rather it became an important component of certain cooking. There are various dishes of using kluwak. Some examples: 1. Rawon: it's a traditonal soup from East Java (Jawa Timur - Indonesia) where the kluwak will give a special taste and color to the soup. 2. Pindang: this is rather similar to Rawon, but the soup will have coconut milk. Black pindang is mainly found in Northern part of Central Java (Jawa Tengah - Indonesia) especially in the regent of Kudus, Demak and Purwodadi. 3. Sambal Kluwak: as in preparing any Sambal, the wet kluwak meat is crushed with garlic, chilli and salt. We can also put used cooking oil to give a greasy but delicious taste.
Storing Kluwak nuts
The dried peeled kluwak is normally nicely package in a plastic container. It can be stored for several months.
The shelled kluwak can also be stored for several months. However, when we buy kluwak from tradional market or shops, usually the meat inside is still tender. After long storage, the meat will be hardened. In this case, the kluwak should be soaked in water/lukewarm water before using it.