In a large mixing bowl, combine the glutinous rice flour, milk, granulated sugar, vanilla extract, and salt. Whisk until the mixture is smooth and free of lumps.

Pour the mixture into a microwave-safe dish or bowl. Cover it loosely with a microwave-safe lid or plastic wrap.

Microwave on high for 1 minute. Stir the mixture, then microwave for an additional 1 minute. Stir again, then microwave for another 30 seconds to 1 minute until the mixture is thick and sticky.

Dust a clean surface with cornstarch. Transfer the mochi mixture onto the surface and let it cool for about 10 minutes.

Once cool enough to handle, dust your hands with cornstarch and divide the mochi into small pieces (about 1-inch squares or rounds).

Roll each piece in cornstarch to prevent sticking. Serve immediately or store in an airtight container at room temperature for up to 3 days.