Gather your glutinous rice flour, mango purée, and sugar in a clean space. Use a heat-safe mixing bowl to combine these ingredients, whisking until the mixture is smooth and free of lumps.

Decide whether you prefer steaming or microwaving your mochi. For steaming, transfer the evenly mixed batter into a heat-safe tray. For microwaving, pour the batter into a microwave-safe dish.

If steaming, place the tray in your steamer and cover it, cooking for about 15 to 20 minutes until set. If microwaving, cook in 1-minute increments, stirring in between, for about 3 to 4 minutes.

Once cooked, carefully remove the tray or dish from the steamer or microwave, allowing the mochi to cool for about 10 minutes.

Dust your work surface with cornstarch, turn out the mochi, and slice it into bite-sized pieces. Dust with more cornstarch if desired.