|Three kinds of sweet potato|
To make these delicious bubbles, cook, peel, and mash the sweet potatoes (microwave, oven, steam, your choice), then combine in a 10:3 ratio by weight with tapioca flour. Add a tablespoonful of boiling water, and use your hands to knead the mixture into a dough. Depending on the sweet potato, you may need to add more flour or more water. The dough should be pretty easy to mold.
For the following steps, I like to work on a cutting board protected with a piece of plastic wrap. Break off pieces of dough and roll them into cylinders that are about a half-inch in diameter. Use a knife to chop the cylinders into pieces about 3/4 of an inch long. (The size really doesn't matter).
|Shaved ice with bubbles and mung bean|
At this point, you can freeze your sweet potato bubbles. From room temperature or the freezer, the following cooking process is the same. Boil some water, then gently drop the bubbles into the water with a spoon, stirring to prevent them from sticking to the pot. Keep the water at a simmer and stir occasionally. When the bubbles float to the surface of the water, they should be ready. Taste one just to make sure--it shouldn't taste floury.
The bubbles can be eaten hot or cold--once cooked, they can cool to room temperature without getting mushy, but I wouldn't put them in the refrigerator. I like to eat these with hot water with brown sugar dissolved in it. These are also commonly found as a topping for Taiwanese shaved ice (baobing).