In a microwave-safe bowl, whisk together the flour, sugar, and matcha powder. Add the water and whisk until smooth.
50 g glutinous rice flour, 25 g sugar, 0.5 tsp matcha powder, 90 ml water
Loosely cover the bowl with plastic wrap or a kitchen towel. Microwave on high for 2 minutes. Remove and stir with a damp spatula.
Cover and microwave for another 30 seconds, until the dough is slightly translucent.
Place a sheet of parchment paper on your work surface and generously dust it with cornstarch.
cornstarch, for dusting
Transfer the mochi dough onto the parchment. Dust the top with more cornstarch. Knead briefly.
Divide the dough into 4 equal pieces. Flatten each into a circle with your hands.
Place the red bean paste in the center of each dough round.
200 g red bean paste
Gather the edges to enclose the filling and pinch to seal.
Gently brush the assembled matcha mochi to remove any excess cornstarch.
Notes
If the dough is too sticky, add more starch. The dough will be very hot when it comes out of the microwave, but it’s important to work it while it’s hot. You can let it cool slightly, but there’s a risk it will cool too much. Don’t hesitate to use large spoons, chopsticks, or spatulas to handle it. Personally, I like to use a pestle in my mortar