Prepare the Toasted Flour: Place some raw glutinous rice flour in a dry skillet over low heat. Toast for 3-5 minutes, stirring constantly, until it turns a very light tan color and smells fragrant. Set aside in a bowl to cool completely.

Make the Dough Batter: In a large bowl, whisk together the 120g glutinous rice flour, 30g cornstarch, 10g strawberry powder (if using), and 20g sugar. Slowly pour in the 180g of milk while whisking clockwise until you have a smooth, lump-free, pink batter.

Steam the Dough: Pour the batter through a fine-mesh sieve into a heat-proof bowl. Cover the bowl tightly with plastic wrap and poke a few small holes in it with a toothpick. Place the bowl in a steamer over boiling water, cover, and steam on medium heat for 30 minutes. Do not open the lid during steaming.

Knead the Dough: Carefully remove the hot bowl from the steamer. The dough should be fully set. Add the 20g of softened butter directly onto the hot dough. Using a silicone spatula, roughly mix it in—the residual heat will melt the butter. Once it's cool enough to handle (around 40°C / 105°F), put on food-safe gloves (or coat your hands in the toasted flour), and transfer the dough to a surface dusted with toasted flour. Knead, pull, and stretch the dough for 5-8 minutes until the butter is fully incorporated and the dough becomes very smooth, elastic, and no longer sticky. You now have a beautiful strawberry mochi dough.

Make the Filling: While the dough cools, prepare the filling. In a clean, chilled bowl, combine the 250g of cold heavy cream, 18g of sugar, and 25g of strawberry jam. Using an electric mixer, beat on medium speed until the cream reaches stiff peaks—it should hold a firm shape when you lift the beaters.

Chill the Filling: Transfer the strawberry cream filling into a piping bag. Seal the end and place it in the refrigerator to chill and firm up for at least 10-15 minutes.

Assemble the Mochi: Dust your work surface with more toasted flour. Divide the large dough ball into 9 equal smaller pieces (about 30-35g each). Roll each piece into a ball. Keep the pieces you aren't working with covered under plastic wrap to prevent drying.

Shape the Wrappers: Take one dough ball and flatten it with a rolling pin into a circle about 10-12 cm (4-5 inches) in diameter and 0.3-0.5 cm thick. Remember to dust your rolling pin with toasted flour to prevent sticking. The dough is very forgiving; if the edges crack, you can gently pinch them back together.

Fill and Seal: Cup a dough circle in your hand. Pipe about 20-25g of the chilled cream filling into the center. You can pipe a small dot of extra strawberry jam into the center of the cream.Pipe in another layer of cream. Gently gather the edges of the dough around the filling, pinching them firmly at the top to seal. If needed, dust the sealing area with a little toasted flour to help it close. Use scissors to trim any excess dough at the top for a neat finish.

Serve: Place the finished strawberry mochi sealed-side down in a paper liner.

Garnish with a halved or whole strawberry on top. Enjoy immediately for the best texture, or store them in an airtight container in the refrigerator for up to 2 days.