Soak the oatmeal in 1 1/2 cups of water for ten minutes
Blend the soaked oatmeal (and the soaking water) in a blender or food processor together with the defrosted fruit pulp or fruit for 1 minute.
Pour the blended mixture into a large pot with 4 1/2 cups water (or 6 1/2 cups of cold water if serving cold).
Add the piloncillo or brown sugar and cinnamon sticks.
Bring the mixture to a slow boil. Simmer the mixture (covered) for 10-12 minutes.
Strain the mixture through a fine strainer and serve hot or cold.