As the legend goes, a 19th-century Catalan farmer was out experimenting in his fields when he came up with a new kind of longer, juicier green onion, the calçot. In creating the onion, the farmer produced much more than a new vegetable; he also paved the way for the rise of an idiosyncratic, and distinctly Catalan, cultural event.

Dear Culinary Backstreets, I’ll be in Spain during the December holidays and I’m wondering if Barcelonans eat any special meal on Christmas? If so, what is it and where in the city could I try it?