Wash and hull the strawberries. Pat them dry.
Wrap each strawberry in a thin layer of sweet bean paste if desired.
In a microwave-safe bowl, whisk together glutinous rice flour, sugar, and water until smooth.
Cover loosely with plastic wrap and microwave for 1 minute. Stir.
Microwave for another 1–2 minutes until the dough becomes translucent.
Dust your work surface with cornstarch. Transfer the dough onto it.
Divide the dough into portions and flatten each into a circle.
Place a prepared strawberry in the center of each circle and wrap the dough around it, sealing the edges.
Dust the finished mochi lightly with cornstarch to prevent sticking.