In a bowl, mix glutinous rice flour, matcha powder, and sugar.

Slowly add water and stir until smooth.

Transfer the mixture to a microwave-safe dish and cover with plastic wrap.

Microwave on high for 1 minute, stir, and then microwave for another minute.

Stir again, then microwave for 30-second intervals until the mixture is slightly translucent and sticky.

Dust a clean surface with cornstarch, pour the mochi mixture onto the surface, and let it cool slightly.

Once cool enough to handle, cut into small pieces and shape as desired.

Optionally fill with sweet red bean paste or fruit before sealing the edges.

Dust with more cornstarch to prevent sticking and serve.