Make the filling: Mix the chopped chives, baking soda, salt, sugar, and oil together. Toss well and let sit for 1 hour to soften the chives. (If you want them to soften faster, you can knead them a bit instead of waiting the full hour.) Drain the mixture in a colander to remove excess liquid. (This recipe does not require stir-frying the filling, but if you prefer a softer texture, you can stir-fry it briefly.)

Make the dough: In a mixing bowl, combine the tapioca starch and rice flour. Gradually add the boiling water, stirring with a wooden spatula until combined. When the dough is cool enough to handle, knead by hand. Gradually add the remaining water and oil, kneading with the heel of your hand until the dough is smooth, elastic, and forms a ball. Continue kneading until all the water and oil are incorporated and the dough is soft and pliable.