Make the puri dough with fine semolina, a little all-purpose flour, salt, and water
Knead into a stiff dough and rest it for 20 to 30 minutes
Roll the dough thin and cut into small circles
Deep fry the circles in hot oil until puffed and crisp
Prepare the pani by blending mint, coriander, green chilies, ginger, and tamarind
Add roasted cumin powder, black salt, regular salt, and water to the blended mixture
Strain the pani and chill it
Prepare the filling by boiling and mashing potatoes and chickpeas
Add salt, chaat masala, cumin powder, and chopped onions if desired
Make a small hole in each puri
Fill each puri with the potato-chickpea mixture
Add sweet chutney if desired
Pour the chilled pani into each puri
Serve immediately