White sugar sponge cake
White sugar sponge cake is a type of Chinese pastry.
It is made from rice flour, white sugar, water, and a leavening agent.
Although called a "cake", it is not circular. It is usually purchased as an individual square piece or a small triangle. The cake is white, spongy, and soft. The taste is sweet and sometimes slightly sour due to fermentation of the batter prior to cooking. Like most Chinese cakes it is steamed, which makes it moist, soft, and fluffy. If left exposed to the air, it hardens quickly. It is usually kept under some cover to preserve moistness. It is typically served hot, because when it is cold it is not as soft and moist. The batter is either poured over a bowl in a steamer, a Chinese steamer cloth or aluminum foil. If made from brown rice flour and brown sugar it is called a brown sugar sponge cake.
A Vietnamese version of the cake, bánh bò, differs from the Chinese version in that it often uses coconut milk as an ingredient, and does not have the sourness that often typifies the Chinese version.