Pesto where it is known as "pistou". In contrast with "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. "Pistou" is used in the typical "soupe au pistou", a hearty vegetable soup with "pistou" flavour. The sauce did not originally contain basil, however; instead, cheese and olive oil were the main constituents. Sometimes almonds are used instead of pine nuts, and sometimes mint leaves are mixed in with the basil leaves. It
Pesto 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. In a tight jar (or simply in an air-tight plastic container), covered by a layer of extra-virgin olive oil, pesto can last in the refrigerator up to a week, and can be frozen for later use. Pesto is commonly used on pasta, traditionally with "mandilli de sæa" ("silk handkerchiefs" in the Genoese dialect), trofie or trenette. Potatoes and string beans