The key is to work quickly when encasing the strawberries with the mochi recipe before the dough cools and firms.
- ¾ cup mochiko (sweet rice flour)
- Potato starch (for dusting)
- 8 medium strawberries, stems removed
- ¼ cup koshian (sweet red or white bean paste; optional)
- Find mochiko and koshian at Japanese markets or online.
Mix mochiko, sugar, and ⅓ cup plus 2 Tbsp. cold water in a small bowl. Cover with foil. Bring 2" of water to a simmer in a large pot. Fit with steamer basket; add bowl to basket. Cover pot with a tight-fitting lid. Steam until mixture is translucent and gummy, 20–22 minutes. Remove bowl and stir mixture until a thick, smooth, slightly sticky dough forms.
Meanwhile, schmear strawberries all over with bean paste, if using.
Sprinkle a surface lightly with potato starch; turn out mochi on top. Dust with more starch; cut into 8 pieces. Stretch a piece of mochi around a strawberry to encase; pinch together to close. Roll between your palms to smooth; brush off excess starch. Repeat with remaining mochi and strawberries.
Do Ahead: Strawberries can be wrapped in mochi 4 hours ahead. Store tightly covered at room temperature.