Put the vinegar in a saucepan and heat over medium heat for a few minutes. When it is hot, but not boiling, add the cinnamon stick and remove from the heat.Let it cool.
After a few hours, when it is completely cold, put the vinegar in a glass jar, together with the previously washed raspberries. Cover with a cork or a piece of cloth fastened with a rubber band and let stand in a cool, dry place for 7 to 10 days.