Mix Ingredients: In a microwave-safe bowl, combine the glutinous rice flour, sugar, and matcha powder. Gradually add water and stir until smooth.

Microwave the Mixture: Cover the bowl with plastic wrap and microwave on high for 1 minute. Stir the mixture, then microwave for an additional 1-2 minutes until it becomes sticky and translucent.

Cool and Shape: Let the mochi cool slightly before dusting your hands with cornstarch. Take a small portion of the mochi, flatten it, and if using, place a small amount of sweet red bean paste in the center. Fold the mochi over and seal the edges. Roll gently to form a ball.

Dust and Serve: Ensure each piece is coated in cornstarch to prevent sticking. Serve immediately or refrigerate for later enjoyment.