It's been raining in Seattle, pretty much nonstop for the last 2 weeks (no surprise there) and I ran out of rainy day projects. Desperate to kill time I dug into my collection of cookbooks and found this recipe for Bánh Bò Khoai Tím (Purple Sweet Potato Rice Cakes). This recipe comes from a cookbook by Gia Chánh Hoa Hường, published in the early 70s. The cookbook belonged to my aunt and was passed down to me when she moved to California to be closer to her kids. Like all traditional recipes for Bánh Bò, the leavening comes from Cơm Rượu (fermented rice). If you don't have the time or patience the fermented rice starter...I guess you can replace it with some yeast and see how it always Play with Your Food!

Translated from the original recipe above:

-150g purple sweet potatoes
-350g sugar
-300g rice flour
-3 tbs Cơm Rượu
-pinch of alum
-180ml water from boiling the potatoes
-2 egg whites

Peel potatoes and measure out 150g. Cut potato into cubes and boil with a pinch of alum until potatoes are tender. Weigh the potato mixture and adjust to the liquid amount to get 330g (150g potato + 180g potato water = 330g). Mix together potato mixture, fermented rice and rice flour until a smooth dough is achieved. Proof overnight.

Beat egg whites and sugar to stiff peaks, add the fermented dough and continue to achieve a homogenous mixture. Proof until batter doubles in volume. Steam in porcelain tea cups over high heat for 12 mins.