Place mung beans in a fairly deep pot. Cover with water completely, the water level about an inch and a half above the surface of the mung beans.
Bring to a boil and then lower flame to simmer. Cook until the beans are tender, have broken up and until the beans have absorbed all the liquid leaving only a mush of beans in the pot (very much like cooking rice by absorption).
Watch the pot carefully towards the end so that it doesn't burn. Transfer the mush onto a flat plate to cool it down completely.
When the boiled beans have cooled down completely transfer to a medium bowl and add sugar, flour and a pinch of salt.
Adjust for sweetness if you like it sweeter. Mix thoroughly until it becomes pasty and then shape into patties about 2 inches in diameter.
Batter : Mix all dry ingredients together. Add cold water slowly and stop until you have achieved a nice coating batter.
Heat up a pot of oil until hot. Dip the bean patties in the batter one by one and fry until a light golden brown and crispy.