The name pesto is derived from the marble mortar traditionally used to grind it. Ideally it's made from the leaves from basil plants less than two months old, crushed with garlic, pine nuts, and salt. Add extra virgin olive oil, parmesan and pecorino cheese.This classic version is often called pesto alla genovese.
Plenty of alternative versions exist; instead of basil you can use spinach, rocket, other herbs or even courgette. Ligurians also make pesto bianco, with pine nuts, milk or cream, parmigiano, bread crumbs and fresh marjoram. Maró, a pesto made with favas (broad beans) mint, pecorino and garlic, and maybe anchovies, was a favourite of Ligurian sailors, and is now usually made as a condiment for meats.
There are also Sicilian versions, such as pesto rosso, with tomato added, and pesto trapanese, which uses almonds instead of pine nuts, plus cherry tomatoes, garlic and maybe a peperoncino. Pesto di pistacchi comes from Bronte on the slopes of Mount Etna where pistachios grow.
It's not all vegetaian. Pesto alla modenese is rosemary, lardo and garlic; it doesn't go on pasta, but in crescentine and sandwiches. Pesto alla calabrese uses roast red peppers and three kinds of cheese. In the former Duchy of Parma you'll see pesto di cavallo minced horse meat, served raw or in vecchia alla parmigiana.
In June, Genoa holds a Sagra del Pesto, complete with pasta dishes for celiacs.
Images by: Ross Catrow