Pesto alla Genovese

Pesto alla Genovese is basil, pine nuts, garlic, parmesan and olive oil pounded together raw into a bright green sauce. Traditionally it's worked by hand in a marble mortar with a wooden pestle — never cooked, and never made in a food processor by anyone strict about the name, since a spinning blade heats the leaves just enough to dull the colour and the flavour.

What it actually is

Fresh basil leaves, pine nuts, garlic and coarse salt are crushed together with a circular grinding motion — not chopped — until they break down into a rough, oily paste. Grated parmesan and a hard sheep's cheese are folded in, then olive oil is worked in slowly at the end until the sauce loosens to a thick, spoonable consistency.

Because nothing is cooked, the basil stays genuinely bright green and its flavour stays sharp and raw — the entire point of the dish is that nothing about it is softened or mellowed by heat.

How it's served

• Tossed through hot pasta, off the heat, loosened first with a spoonful of the pasta's cooking water.
• As a spread or dip, alongside bread or spooned over vegetables.
• Made fresh, the same day; the basil oxidises and darkens within hours once it's crushed.

Writing it on a menu

• Flag dairy from the two cheeses.
• Note that pine nuts are used, since guests with a tree-nut sensitivity will ask specifically.
• Say if it's made fresh in-house, since the colour and sharpness fade fast in a jarred version.
• Mention which dish it dresses — pasta, potatoes, minestrone — since pesto on a menu is rarely served on its own.