Genoa, the capital city of Liguria, Pesto aioli. Italy and the rest of the world.
Pesto is thought to have two predecessors in ancient times, going back as far as the Roman age. Although likely originating from and being domesticated in India, basil took the firmest root in the regions of Liguria, Italy, and Provence, France. It was abundant in this part of Italy, though only when in season, which is why marjoram and parsley are suggested as alternatives when basil is lacking. In 1944, The New York Times mentioned an imported canned pesto paste. In 1946, Sunset magazine published a pesto recipe by Angelo Pellegrini. Pesto did not become popular in North America until the 1980s and 1990s.
Pesto is traditionally prepared in a marble mortar with a wooden pestle. First, garlic and pine nuts are placed in the mortar and reduced to a cream, and then the washed and dried basil leaves are added with coarse salt and ground to a creamy consistency. Only then is a mix of Parmigiano-Reggiano and Pecorino added. To help incorporate the cheese a little extra-virgin olive oil is added. Potatoes and string beans are also traditionally added to the dish, boiled in the same pot in which the pasta has been cooked.
It is used in Genovese minestrone. Outside of Italy, pesto is sometimes served with sliced beef, tomatoes, and sliced boiled potatoes. Pesto comes in a variety of recipes, some traditional and some modern, as the very noun pesto is a generic term for anything that is made by pounding. A slightly different version of this sauce exists in Provence, where it is known as pistou. In contrast to pesto alla genovese, pistou is generally made with olive oil, basil and garlic only: while cheese may be added, usually no nuts are included in a traditional pistou because no pine trees grow there to provide the nuts. Outside of Italy sometimes, almond, brazil, cashew, hazelnut, macadamia, pecan, pistachio, walnut, or even peanuts are used instead of pine nuts, and sometimes coriander, dill, kale, mint, parsley, rocket, spinach, or wild garlic leaves are mixed in with the basil leaves.