Take boiled chana in a bowl. Add boiled potatoes and mash them together with your hand. Take the tamarind pulp in a deep bowl.
Add salt, black salt, roasted cumin powder, red chilli powder and mix well. Add four cups of water and mix. Add ice cubes and mix properly.
Make a little hole in the puris, put the potato-chana mixture in it, dip in the stirred prepared water and serve immediately.