Sweet Leek Vinaigrette

Sahagún has a dusty, one-horse town kind of appeal; set on the arid Meseta between León and Burgos, it’s a resting place for pilgrims on the Camino de Santiago. In the Middle Ages this was a bustling town of Jews, Moors and Christians nowadays it’s a country backwater, but it does have one claim to fame, its deliciously sweet leeks.

This is a simple recipe that gets even better after a few hours, or even a night, in the refrigerator. But do make sure it is at room temperature when y