Genoa, Liguria — pesto is documented in Genovese sources from the 19th century, though herb pastes in olive oil are ancient in the Mediterranean. The DOP designation for Basilico Genovese protects the specific basil variety. The traditional marble mortar technique is protected by the World Pesto Championship rules.
Pesto alla genovese is among the most globally reproduced Italian preparations, yet the original version — made with specific Genovese basil (Basilico Genovese DOP, small-leafed, not peppery, grown in the Riviera di Ponente soil) pounded in a marble mortar with pine nuts (pinoli), garlic, coarse salt, Pecorino Sardo, Parmigiano Reggiano, and the best Ligurian extra-virgin olive oil, never touched by a blender blade — is a different preparation from its many imitations. The marble mortar method is essential: the blade of a blender heats and bruises the basil, turning it bitter and dark; the mortar bruises and extracts differently, producing a vivid green, slightly textured paste with no bitterness. The preparation is made at room temperature and is never heated.
Pesto alla genovese made correctly in a marble mortar is vivid green — not the dark, slightly grey-green of blender pesto. The basil fragrance is fresh and clean, with no bitterness; the pine nut provides a background sweetness; the Pecorino adds sharpness; the olive oil ties everything together. On trofie pasta (the traditional Ligurian shape) with green beans and potato, it is one of the most purely satisfying pasta preparations in Italian cooking.
Basil: Genovese DOP small-leafed variety, completely dry after washing, leaves only (no stems). In a cold marble mortar, begin with the garlic and coarse salt — grind to a paste. Add the pine nuts; pound to a rough paste. Add basil leaves in batches — work in a circular grinding motion (not vertical crushing), pressing the leaves against the side of the mortar. Add Pecorino Sardo and Parmigiano (equal quantities) when basil is mostly broken down. Add olive oil in a thin stream while continuing to work — the oil should be incorporated to a slightly textured, vivid green paste, not a completely smooth emulsion.
Genovese DOP basil seed is available for growing — even on a windowsill in northern Europe, the small-leafed Genovese variety can be grown and produces better pesto than shop-bought large-leafed basil. The Pecorino Sardo in the traditional recipe (not Pecorino Romano — too sharp) and Parmigiano Reggiano in equal parts is the cheese combination. Pesto should be made and served the same day — it deteriorates in flavour significantly after 24 hours even when stored correctly.
Using a blender — the mechanical blade cuts and heats, turning the basil bitter and dark; the mortar's crushing action is entirely different. Using large-leafed, peppery basil — Genovese DOP basil is not peppery; large-leafed greenhouse basil produces a bitter pesto. Storing pesto with the oil surface not covering — the basil oxidises rapidly; always cover with a generous oil layer when storing.
Giorgio Locatelli, Made in Italy; Anna Gosetti della Salda, Le Ricette Regionali Italiane