Pesto alla genovese is Liguria's defining sauce and one of the most recognized Italian preparations worldwide—a raw, uncooked emulsion of fresh basil, garlic, pine nuts, Parmigiano-Reggiano, Pecorino Fiore Sardo, and extra-virgin olive oil pounded in a marble mortar that captures the aromatic essence of the Ligurian Riviera. The sauce's name derives from 'pestare' (to pound), and the technique—not the recipe—is the critical element: genuine pesto is pounded in a mortar (preferably marble, which stays cool) with a wooden pestle, the circular crushing motion tearing the basil leaves rather than cutting them (as a blade or food processor would), releasing their essential oils gradually and producing a textured, green-gold sauce of unmatched freshness. The basil must be young, small-leafed Genovese basil (basilico genovese DOP), grown in the microclimate of the western Ligurian coast where sea breezes, warm days, and cool nights produce leaves of extraordinary intensity—a single leaf perfumes an entire hand. The garlic is used sparingly (a clove or two per bunch of basil), the pine nuts should be Italian (preferably from Pisa), and the cheese combination—Parmigiano for structure and sweetness, Pecorino Fiore Sardo for salt and tang—is canonical. The olive oil is added last, stirred in to bind the pounded ingredients into a loose, spoonsable consistency. Pesto alla genovese is traditionally served with trenette (flat, narrow Ligurian pasta), trofie (hand-rolled cork-screw shapes from Recco), or mandilli de saea (silk handkerchief pasta—paper-thin lasagne sheets). The Genovese practice of adding a boiled potato and green beans to the pasta water before dressing with pesto creates the classic 'trenette al pesto con patate e fagiolini'—starch, vegetable, and herb in perfect equilibrium.
Pound in marble mortar with wooden pestle—don't cut. Young Genovese basil DOP. Pine nuts, garlic, Parmigiano + Pecorino Fiore Sardo. Add olive oil last. Never cook the pesto—it's a raw sauce. Serve with trenette, trofie, or mandilli.
Chill the mortar before starting—cold preserves the basil's green colour. Add a pinch of coarse salt with the basil—it acts as an abrasive to help break down the leaves. Pound the garlic and salt first, then pine nuts, then basil. The olive oil should be Ligurian Taggiasca if possible. A tablespoon of starchy pasta water stirred into the pesto before dressing helps it coat the pasta.
Using a food processor (cuts leaves, produces different flavour). Using non-Genovese basil. Over-processing to a smooth purée. Cooking the pesto. Using only Parmigiano (need Pecorino Fiore Sardo too). Adding too much garlic. Using poor-quality olive oil.
Marcella Hazan, Essentials of Classic Italian Cooking; Fred Plotkin, Recipes from Paradise—Life and Food on the Italian Riviera