How to make Harbin mung bean starch

Dissolve mung bean starch in water. Spare (not too much water, try using chopsticks and pick up some, if it can be thick).

Put enough water in the pot (a catty of flour should be put in half a basin for washing your face, which has not been measured), then boil it, slowly pour in mung bean starch, and stir while pouring it until it becomes transparent. Then pour it out and let it cool. I heard that some alum should be added, not too much, just a little, otherwise it will be very pink.