In a heatproof bowl, mix together mochiko, water, and sugar until well combined.
Steam the mixture for 15 minutes. Do not forget to cover the steamer's lid with a towel to catch the condensation. Half way cooking, stir the mixture and immediately steam again to finish cooking. The color of cooked mochi should be opaque and the texture should be smooth and sticky.
Cover the work surface with cornstarch. Transfer the cooked mochi on top.
Assemble
Once it has cooled down a bit, cover the mochi, rolling pin, and your hands with cornstarch. Divide the mochi into 6. Roll each ball into a 4-inch/10 cm round.
Put about 1 tablespoon of sweet red bean paste on the center. Pinch the four corners of mochi together to wrap the anko. Then, pinch the remaining corners together to seal the filling completely. Put the seam down.
With a clean scissor, snip the top of mochi. Put a strawberry at cut. Best enjoyed in within 2 days.