Sweet potato doughnut balls (kai tao)

Peel the sweet potato and cut into about one-inch chunks.

Steam over a pot of water, the water below the rack, 10 to 15 minutes until completely soft; a fork should meet zero resistance.

Stir sugar and a little salt into the hot sweet potato until the sugar dissolves.

Add tapioca starch and all purpose flour; sift in a little baking powder; mix.

Work in coconut milk a tablespoon at a time until the dough rolls easily into a ball without sticking but is still moist; 2 tablespoons here.

Roll into balls about a heaped measuring teaspoon each. The balls can be refrigerated and fried the next day.

Heat vegetable oil to 325F, no higher than 350F.

Drop in the balls and keep them moving constantly, both while they sink and after they float, frying a full 5 minutes even if they look done.

Roll on paper towel to absorb surface oil, then cool on a rack; eat while still warm.