Place the rice and cinnamon stick in a large glass bowl and add the 4 cups of hot water. Cover the bowl with a dish or plastic wrap, then let it soak overnight, or at least 8 hours. *Please seeNOTES
The next day, pour the rice, cinnamon, and water into your blender and process until it becomes a smooth, watery paste.
Using a strainer or sieve, strain the mixture into a wide mouth pitcher, stirring to help the liquid pass through.
Add the milk (if using), vanilla extract, and the rest of the water. Stir in the sugar, adjusting the amount to fit your taste. Let the drink chill in the refrigerator. Stir the Horchata before serving, since the rice mix tends to settle at the bottom. Serve in glasses with ice cubes.
Video
Notes
If you have a Vitamix or other high-performance blender, you won’t need to rest the rice to soften it, as the blender will be powerful enough to grind the hard rice grains. Additionally, you probably won’t need to use a sieve or strainer to strain the rice water, as the rice mixture will be very finely processed.
Always taste the drink before adding the sugar. You might need more or less sugar than the amount indicated in the ingredients.
If you feel that the consistency of the Horchata is too thick or dense for your taste, simply add more water.