1. Place the rice and cinnamon in a spacious, heat-resistant mixing bowl and add enough boiling water to cover. Top with plastic wrap and set aside for eight hours, or overnight.

2. Pour the mixture into a fine mesh strainer, drain well, and discard the water.

3. Place half of the softened rice, cinnamon sticks, and four cups of water in a blender and liquefy. Repeat with the remaining rice and water.

4. Pour the mixture through a double layer of cheesecloth set in a fine mesh strainer over a bowl. Discard the solids.

5. Add the sugar and vanilla to the bowl and mix until dissolved.

6. Pour the Agua de Horchata into a pitcher and chill 2–3 hours before serving.

7. Serve over ice in individual glasses.