The sap of the khejur, the date palm, is tapped at night in the cold months by shiuli, tappers who cut the crown and hang a clay pot. It is boiled down the same morning. Left liquid it is jhola gur; set hard it is patali.
It only works when the nights are genuinely cold, which in Bengal means roughly mid-December to mid-February. Outside that window what is sold as nolen gur is cane jaggery with a flavouring.
Every sweet in the city gets a winter version: nolen gur sandesh, nolen gur rosogolla, nolen gur mishti doi, nolen gur ice cream. The rosogolla in particular goes from good to remarkable.
The trade is shrinking. There are fewer tappers each year, and the skill does not transfer easily.
