Ma Tai Go (Steamed Water Chestnut Cake)

Variations

• Cold, unfried: the one in the photograph comes from a Guangzhou dim sum house and is sliced and served cold. Frying gives it a golden skin and softens the inside again.
• With white sugar: white sugar in place of brown or slab sugar gives a clear golden cake. The deep brown in the photograph is the colour of a less refined sugar.
• Layered with coconut: alternating the water chestnut mixture with a coconut milk mixture and steaming it in layers is common in Hong Kong. Each layer has to be nearly set before the next goes on, or they run together.
• On the same dim sum trolley as lo bak go: both set pieces into a starch batter, steam it, and are chilled, sliced and fried. Lo bak go wets its rice flour with the water the radish gives up; this wets its water chestnut flour with sugar syrup.

Tips

• Water chestnut stays crunchy when cooked. Har gow only says to use it when there is no bamboo shoot: "Shrimp and wrapper are both soft, so with nothing crunchy in there you tire of them by the third one. Water chestnut or blanched celery heart will stand in". Why that works is half of this cake. A water chestnut’s cell walls are bound together by phenolic compounds such as ferulic acid, so heat does not loosen them the way it softens most vegetables; it is why tinned water chestnuts are still crisp. Boiled in syrup, steamed for 35 minutes and fried again, the pieces still crunch.
• The flour goes the other way. Water chestnut flour is the same corm ground and washed until only its starch is left. Out of the cells, that starch meets water and heat and sets into a clear, springy gel. The starch in the pieces is shut inside walls that will not give; the starch in the flour is outside them. The two textures in one slice are that difference.
• Pour it half-cooked. Lo bak go gives the same reason: "Tipping the flour into the hot radish and its liquid partly gelatinises the starch into a thick batter that does not settle in the steamer. Mixed cold, the radish sinks and the water rises". Steam the pieces in a thin slurry and they sink to the bottom, leaving plain gel on top. Stirred over the heat until about half translucent, the batter holds them where they are.
• Keep stirring. The slurry starts to cook the moment it meets the hot syrup, and without stirring it sets into lumps on the bottom of the pan. Those lumps do not smooth out in the steamer.
• It slices only when cold. Warm gel sticks to the knife and tears. Once it has cooled and firmed it cuts cleanly and keeps its shape in the pan.
• Do not keep turning it in the pan. As with lo bak go, the point of frying is the skin, and a slice moved before the skin forms sticks.