Pesto is an Italian sauce, generally attributed to the Liguria region of Northern Italy, specifically the city of Genoa (pesto alla Genovese). It has been known, in various forms, since Roman times, and probably originated in North Africa.
Today, basil, garlic, pine nuts, olive oil, and equal parts Parmigiano Reggiano and Pecorino Romano cheese are the main conventional ingredients. The sauce did not originally contain basil, however. Instead, cheese and olive oil were the main constituents. It is commonly used on breads and pasta, though its use is not restricted to these; the sauce is highly versatile. In commercial pesto, cashew nuts are often used instead of pine nuts, as they are cheaper and have a similar texture.
A German variety uses ramsons leaves instead of basil.
- Sun-dried tomato and walnut pesto recipe (http://www.mediterrasian.com/delicious_recipes_pesto.htm)