You may have known Genoa primarily for its salami or its brash explorer, but the city's most direct effect on your life away from Italy may be through its cultivation of one of the world's best pasta sauces. The sublime blend of basil, extra-virgin olive oil, garlic, pine nuts, and grated pecorino and Parmigiano Reggiano cheeses that forms pesto alla Genovese is one of Italy's crowning culinary achievements, a concoction that Italian food guru Marcella Hazan has called "the most seductive of all sauces for pasta." Ligurian pesto is served only over spaghetti, gnocchi, lasagna, or—most authentically—trenette(a flat, spaghetti-like pasta) or trofie(short, doughy pasta twists), and then typically mixed with boiled potatoes and green beans. Pesto is also occasionally used to flavor minestrone. The small-leaf basil grown in the region's sunny seaside hills is considered by many to be the best in the world, and pesto sauce was invented primarily as a showcase for that singular flavor. The simplicity and rawness of pesto is one of its virtues, as cooking (or even heating) basil ruins its delicate flavor. In fact, pesto aficionados refuse even to subject the basil leaves to an electric blender; Genovese (and other) foodies insist that true pesto can be made only with mortar and pestle.