Things You'll Need
Mortar and pestle (or other grinding tool)
Mung bean starch is a thickener commonly used in Asian cuisine. You can use the starch as a thickener in soups, stews, sauces, stir fries and many other recipes or you can process it and turn it into jelly and Asian style cellophane noodles. The starch you extract at home will not be as pure as the starch you purchase commercially, but it can still be used in a similar fashion and is still perfectly edible.
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Pour the mung beans into a large mixing bowl, cover them with water and soak the beans overnight.
Strain the mung beans from the soaking liquid (reserve the liquid in a separate bowl) and grind them down to a fine paste with a mortar and pestle.
Press the mung bean paste through a food mill and reserve the liquid that is extracted. Repeat this process until all of the liquid has been removed from the ground mung beans. A small amount of liquid from the reserved soaking fluid can be added to the paste to remove as much starch as possible.
Strain the liquid through cheesecloth into a storage container to remove any leftover solids. Squeeze the cheesecloth to get as much liquid out of it as possible.
The starch extracted will not be pure, but you can still use it as a thickener. The liquid will set up as it is cooled in the fridge.
Do not store the liquid starch for longer than a week. It will begin to spoil.