Cook the brown rice according to the package directions.
Let cool for a few minutes, and then add the cooked rice to a blender, along with ½ cup water. Process until smooth, scraping down the sides as needed.
Add additional water as needed, 2 to 3 tablespoons at a time, to reach the desired consistency.
Transfer to a small bowl and let cool, and then serve or store until ready to use. Store in an airtight container in the refrigerator for 3 to 5 days or in the freezer for 4 to 6 months.