1.In a medium bowl, stir together the flour, sugar and cinnamon. Using a fork, blend in the white vinager. When dough forms a ball, turn out onto a lightly floured surface and knead until smooth, about 15 minutes. Cover and refrigerate for about 2 hours. 2.Heat 1 inch of oil in a deep heavy skillet to 365 degrees F (180 degrees F). On a lightly floured surface, roll 1/3 of the dough out into a big circle as thin as paper. Cut into 8 (5-inch) circles. Wrap each circle around a cannoli form, and seal with egg yolk. 3.Fry 2 or 3 at a time until golden brown. remove with tongs to drain on paper towels. Carefully remove shells from forms while they are still hot, or they may become stuck. Footnotes