In a large mixing bowl, mix together the glutinous rice flour and sugar.
Add in the milk a little at a time (you may not need the whole thing), while mixing after each addition, until it becomes a dough. Knead for a few minutes. The dough should not be sticky nor too dry, it should have a glossy finish. Add more milk or more flour a little at a time if it’s too dry/wet.
Grab a small piece of the dough and roll into a ball that’s about 1cm.
Drop the milk balls in a saucepan of boiling water, and stir continuously to prevent them from sticking to the bottom. Cook them for a few minutes, until they float to the top. Place them in an ice water bath for 10 minutes to cool off (this step makes them chewier).