Remove and discard the seeds from kokum. Rinse once and drain the water. Soak in 1 cup of hot water for 30 minutes.
Roast the cumin seeds in a small pan and allow them to cool.
Massage the kokum in the water. Squeeze out all the extract and discard the rinds. Place a fine strainer over a medium bowl and strain the kokum water through it.
To a small blender jar, add ginger, garlic, green chilli, beet, cumin seeds, and salt. Add half of the coconut milk and blend until smooth. Add the remaining coconut milk and blend again until it is smooth.
Pour the blended coconut mixture through the strainer into the same bowl as the kokum water. Use a silicone spatula to press down the puree.
Add the cold water a little at a time to help take out more from the remains in the strainer. Garnish with chopped cilantro. Add ice cubes. Give a quick stir and serve.