Kolkata's version swaps in whole-wheat shells and a mashed-potato filling for the semolina puris and pea mix used in Mumbai's pani puri — and its tamarind water is deliberately sharper and spicier, built to jolt rather than soothe.
Thin, whole-wheat puris are cracked open and filled with mashed potato spiced with tamarind pulp and black salt, then dunked in fiery tamarind-chili water and handed over one at a time to eat in a single bite. Street carts across Kolkata assemble it fresh at the moment of order.