How to make mung bean syrup at home? It's very simple. Wash the mung beans and freeze them in the refrigerator overnight, then boil them with water. The frozen mung beans are very good. After boiling, add rock sugar and simmer for 10 minutes, so that the mung bean syrup is ready for consumption. It is not sweet or greasy, relieves heat and thirst, and relieves fire and detoxification.