In a microwave-safe bowl, mix the glutinous rice flour and sugar together.

Gradually add water to the flour mixture while stirring until smooth.

Cover the bowl with plastic wrap and microwave on high for 1 minute. Stir the mixture, then microwave for another minute.

Remove the bowl and stir the mixture again. If it's not yet translucent and sticky, microwave for another 30 seconds.

Dust a clean surface with cornstarch or potato starch. Transfer the hot mochi dough onto the surface.

Dust your hands with starch and knead the mochi briefly until smooth. Divide into small pieces and shape as desired.

If filling with red bean paste, flatten a piece of mochi, place a small amount of filling in the center, and pinch the edges to seal.

Dust the finished mochi with more starch to prevent sticking. Serve immediately or store in an airtight container.