Crispy shells with spicy mint water (Pani puri)

1. The night before, soak the chickpeas in plenty of water; the next day boil them until tender (about 45 minutes). Boil the potatoes in their skins, peel and dice small. Mix the two and sprinkle with chaat masala and salt.

2. For the pani, blend the mint, coriander, green chillies and a little water until smooth. Stir in the remaining cold water, the tamarind paste, the dry-toasted crushed cumin seeds, the chaat masala and the salt. Strain and chill for at least 1 hour.

3. For the shells, knead the semolina, flour and salt with a little water into a firm dough, cover and rest for 20 minutes. Roll out thinly, 2 mm thick, and stamp out rounds with a 5 cm cutter. Keep the rounds under a damp tea towel so they don't dry out.

4. Heat the oil in a smaller, deep pan and add 4-5 rounds at a time. Press them gently with a slotted spoon until they puff up, then turn and fry into crisp golden balls. Lift onto kitchen paper and cool completely.

5. To serve, poke a hole in the top of each shell with your thumb and add a teaspoon of filling.

6. Just before eating, dip each one into the ice-cold pani and eat it in one go!

Tip: Mumbai's favourite street food, known as "puchka" in Kolkata and "golgappa" in Delhi. Each shell must be eaten in a single bite, as the liquid soaks it: that crisp-spicy-cold "explosion" is the whole point. Ready-made puri shells are sold in Indian shops.