Traditionally, this sauce is made by hand using a mortar and pestle. If you are making it in a blender, pulse-blend the ingredients to maintain a fairly rough texture. This recipe makes 375 ml (1½ cups).
If you will not be using the pesto immediately, store in the refrigerator in a tightly closed jar, covered with a thin layer of olive oil, where it will keep for up to a week.
A potato is not always added to this dish, but it is said that its starch helps the pesto to hold o