Liguria
The canonical Ligurian pesto made in a marble mortar — Genovese basil (DOP), Ligurian pine nuts, garlic, coarse salt, Pecorino Sardo and Parmigiano, emulsified with extra-virgin Ligurian olive oil. The mortar method produces a coarser, more aromatic result than a blender because it ruptures cell walls rather than cutting them, releasing volatile compounds without the heat that oxidises the chlorophyll.
Intensely aromatic, grassy and sweet from the basil; pine nut richness; garlic sharpness; the olive oil binds it into something greater than the sum of its parts — one of the world's great sauces
{"Use only Genovese DOP basil (small leaves, sweet, not peppery) — large-leafed basil varieties are more bitter and peppery","Begin with salt and garlic in the mortar — the salt acts as an abrasive and the garlic paste becomes the foundation","Add basil in stages and work in a circular motion — pestling straight down bruises rather than ruptures the leaves","Add pine nuts after the basil is creamy — they emulsify into the paste","Incorporate olive oil last and by hand off the mortar — stir it in with a spoon rather than pestle to preserve the green colour"}
{"Add an ice cube or work over a bowl of ice during the mortar process — cold temperature preserves the vibrant green colour","The ratio of Pecorino to Parmigiano is 1:3 — Pecorino for sharpness, Parmigiano for depth","Never heat pesto — thin with pasta water off heat and toss cold; the heat of the pasta is enough to meld it"}
{"Using a blender — the heat from friction oxidises the chlorophyll and the pesto turns dark brown within an hour","Wrong basil variety — large-leafed basil produces a bitter, mentholated pesto","Too much garlic — one small clove per 2 bunches of basil is traditional in Genova; more unbalances the sauce"}
Il Pesto Genovese — Disciplinare della Denominazione (Comune di Genova)