Of all the pesto recipes in Food of the Italian Islands, pesto from Carloforte in Sardinia is the one that looks the most like pesto alla genovese, which makes sense because Carloforte on the Isola di San Pietro was founded by fishermen originally from the region of Liguria. The addition of tuna is a nod to the island’s main export.

The Italian south’s resources and position as a crossroads in the Mediterranean have made it a target for conquest and…