Combine mint leaves, coriander leaves, green chillies, ginger, and tamarind pulp in a blender and blend until smooth.
Using a sieve, strain the combined mixture to get rid of any coarse fibres to get a smooth consistency.
Mix in black salt, cumin powder, chaat masala and salt to enhance the flavour.
Add chilled water to the mixture, adjusting the quantity based on how strong or mild you want the flavour.
Serve the water with pani puri or golgappas after it has been chilled for at least 30 minutes.