In a large mixing bowl, whisk together glutinous rice flour, cornstarch, and granulated sugar. Gradually stir in milk to achieve a smooth, lump-free batter.

Pour the mochi batter into a shallow dish, cover tightly, and steam for about 20 minutes until firm and slightly translucent.

Remove the dish, let it cool slightly, then add oil and optional dragon fruit juice. Knead gently until smooth.

Dust hands with cornstarch, pinch off small pieces of dough, and flatten into thin circles.

Place a piece of ripe banana in the center, fold the edges over, and pinch to seal completely.

Roll each sealed mochi in coconut flakes to coat evenly.

Optionally dust with powdered sugar or drizzle with melted chocolate before serving.