It exists because a 1930s kebab shop's grilled skewers were too greasy to eat on the move — the fix was wrapping them in paratha, and the roll only got its name in 1964 when the shop swapped its heavy iron skewers for bamboo ones, called 'kathi' in Bengali.
Skewer-grilled meat or paneer is tossed with onion and spice on a hot griddle, then rolled inside a layered, egg-brushed paratha with chutney and a squeeze of lime, wrapped in paper for eating on the go. Kolkata's New Market area and roll stalls citywide sell it as a fast lunch or late-night snack.