To begin, take a large bowl and combine the semolina, all-purpose flour, baking soda, and salt. Gradually add water, about 1 tablespoon at a time, and knead into a stiff dough. The dough should be firm yet pliable. Cover it with a damp cloth and let it rest for 20-30 minutes.

Meanwhile, prepare the pani (tangy water). In a blender, combine the mint leaves, cilantro, green chili, ginger, roasted cumin powder, chaat masala, black salt, and tamarind pulp. Add a little water and blend until smooth. Strain the mixture into a large bowl and add the remaining cold water. Adjust salt to taste and refrigerate the pani for at least 30 minutes to chill and enhance the flavors.

Once the dough has rested, divide it into small portions. Roll each portion into thin discs, about 2 inches in diameter. Keep the rolled discs under a damp cloth to prevent drying.

Heat oil in a deep pan for frying. Once the oil is hot, carefully drop a few discs into the oil, frying them on medium heat. Press lightly with a slotted spoon to help them puff up. Fry until they turn golden and crispy. Remove and drain on paper towels. Repeat the process for all the puri discs.

For the filling, mix the boiled mashed potatoes with the boiled chickpeas (if using), chaat masala, cumin powder, and salt. Ensure the mixture is well seasoned. This filling provides the base flavour for the puri.

Before serving, ensure the pani is chilled and the puri are crispy. If the puri lose their crispiness, briefly toast them in a preheated oven at 180°C (350°F) for 3-5 minutes.

To assemble the pani puri, gently crack the top of each puri to create an opening. Fill each one with the potato mixture and a few chickpeas, if desired.

Serve the filled puri alongside a bowl of chilled pani. To enjoy, dip the filled puri into the pani and eat in one bite to experience the full burst of flavors. You can also offer sweet tamarind chutney as a condiment for an additional layer of flavour.