Mexican Horchata is a sweet and cool drink made with rice and cinnamon, also known as Mexican agua de horchata.
Add the rice and cinnamon stick, vanilla bean if using, to a large glass bowl and pour 4 cups of hot water on top.
Cover the bowl with plastic wrap, then let it soak overnight, or for at least 8 hours.
The next day, transfer the mixture to a high-speed blender and process until it becomes a smooth, watery paste.
After that, use a sieve, and strain the mixture into a pitcher.
Add the milk, vanilla extract, and the rest of the water to the pitcher.
Stir in the sugar, and taste to see if you need to add more.
Chill in the refrigerator before serving. Always stir the Horchata before serving.
Add ice cubes to glasses and pour the drink. Sprinkle with cinnamon.