By JEFF PACHOUD / AFP France’s favourite condiment, Dijon mustard, is hard to find these days, with signs on supermarket shelves warning the lucky few who spot jars that they can only take one home. France’s favourite condiment, Dijon mustard, is hard to find these days, with signs on supermarket shelves warning the lucky few who spot jars that they can only take one home. A heatwave across the ocean in Canada, the world’s top mustard seed producer, is to blame for the drastic shortage that has dragged on for months in France. Canada supplies around 80 percent of the mustard seeds used by Fren…