The date coincides with Poland’s Independence Day.
The pastry is made from semi-puff dough and filled with white poppy seed paste, nuts, raisins and orange peel, among other ingredients.
Since 2008, the traditionally baked version has had the protected designation of origin status in the European Union.
But the tradition is about more than selling pastries, said Mateusz Kril of the Rogal Museum of Poznań.
"It was created so that people would share them and, like St Martin, do good," he told the PAP news agency.
"That is why I think the 11 November celebrations are special in the context of our country.”
According to local legend, the custom began in 1891, when parish priest Jan Lewicki urged worshippers to help the needy, following the example of St Martin.
Confectioner Józef Melzer, who attended the service, was inspired to bake several trays of the pastries.
He sold them to wealthy residents and gave them to the poor.
Other bakers in the city later joined in.
The history may go back further.
The earliest known mention of pasties baked for St Martin’s Day is a newspaper advertisement from 1852, and the name "rogal świętomarciński" first appeared in print in 1860.
Today, members of the Poznań Guild of Confectioners and Bakers sell an average of 250 tonnes of the pastries on St Martin’s Day.
Over the whole year, sales reach about 500 tonnes, or roughly 2.5 million pieces.
Nearly 100 producers hold certificates that allow them to make the original product.
The origin of the pastry’s shape is disputed.
One legend says it resembles a horseshoe lost by St Martin’s horse.
Other accounts link it to pagan offerings, or to the crescent on the Turkish banners that King Jan III Sobieski captured at the Battle of Vienna in 1683.
(ał)
Source: PAP