In a microwave-safe bowl, combine glutinous rice flour and sugar. Gradually whisk in water until smooth and lump-free.

Cover with a wet paper towel and microwave on high for 1 minute. Stir, then repeat two more times until thick and translucent.

Allow the mochi dough to cool for about 5-10 minutes.

Dust a clean surface with cornstarch, transfer the dough, and sprinkle with more cornstarch. Cut into eight equal pieces.

Optionally freeze the cut pieces for 20 minutes for easier handling.

Flatten each mochi piece, place a chunk of banana in the center, and pinch the edges to seal.

Refrigerate filled mochi for one hour before serving.

Serve mochi on its own or with a scoop of vanilla ice cream.