Soak 1 bowl of white peas and 1/2 bowl of white chickpeas in water for 8 hours, adding a little salt while soaking.
Drain the soaked white chickpeas and white peas, then put them in a pressure cooker. Add 1 glass of water and pressure cook for 5-6 whistles until they are very soft.
Once cooked, lightly mash some of the white chickpeas and white peas in the cooker to thicken the liquid, but leave some whole for texture.
Transfer the cooked and lightly mashed white chickpeas and white peas with their liquid into a bowl.
Add about half of a medium-sized boiled potato, cut into small pieces, to the mixture and mix well.
Add finely chopped tomato, chopped onion, and some fresh coriander leaves to the bowl.
Add a little black salt and adjust regular salt to taste, remembering that some salt was used during soaking and boiling.
Add finely chopped green chilli, mint leaves (or mint chutney), a small amount of Pani Puri masala, and chaat masala.
Add roasted cumin powder, red chilli powder, and amchur powder (or grated raw mango).
Add tamarind-date chutney and sugar (or sugar powder).
Mix all the ingredients thoroughly.
Serve the chaat hot. You can also add some salty sev or crushed dry puri for extra crunch, or enjoy as it is.