Whisk yoghurt free of lumps, add chaat masala, jeera powder, a pinch of sugar and mix well. Chill for 15 mins.
Boil potatoes till fork tender. Peel and crumble them lightly. If using boiled sprouts or kala channa (dark coloured chickpeas), slightly crumble them and add to the potato. Add chaat masala, salt, kala namak (Black salt), jeera powder - mix well and keep aside.
Take 5-6 pani puris / Golgappe in a plate, slightly crush them at the top to stuff the filling. Add the potato - sprouts mixture, top with chilled yoghurt, add the chutneys (sweet and coriander-mint), sprinkle a little jeera powder and sev and garnish with green coriander.