1In a medium bowl, combine the wheat starch, tapioca starch, and salt. Make a well in the center and pour in about 3/4 cup plus 2 tablespoons of the boiling water. Use a wooden spoon or rubber spatula to stir. The dough will look white and shaggy.
2Add the oil, stirring it into the dough. If the dough looks dry, and 1 to 2 tablespoons of boiling water. If it looks too wet, add a bit more wheat starch. The dough should have the consistency of modeling clay.
3Transfer the dough to an unfloured work surface and knead by hand until it’s very white and smooth, about 2 minutes. Cut the dough into 3 or 4 pieces, according to the dumpling recipe you’re using, seal in zipper-top plastic bags, and set aside to rest for 5 minutes.