Pesto

Pesto is a raw sauce from Genoa in northwest Italy, made from fresh basil, pine nuts, garlic, salt, hard aged cheese and olive oil. The name comes from the Italian for "pounded", because it was first made in a mortar and pestle. It is best known tossed with pasta, but it also goes on sandwiches, soups, fish and vegetables.

How to do it

For enough to sauce 400 g (14 ounces) of pasta:

1. Lightly toast 30 g (1/4 cup) of pine nuts in a dry pan if you like. Let them cool.
2. Pound or pulse 1 garlic clove with a pinch of coarse salt into a paste.
3. Add the pine nuts and grind them coarsely.
4. Add 50 g (about 2 packed cups) of basil leaves and grind until finely chopped.
5. Stir in 40 g (1/2 cup) of finely grated Parmigiano Reggiano or a mix with Pecorino.
6. Stir in 80 to 120 ml (1/3 to 1/2 cup) of extra virgin olive oil. Season.

A food processor works too. Pulse rather than run it, so the basil does not get hot and bitter.

How to use it

Toss pesto with hot pasta off the heat, loosened with a few spoons of the pasta cooking water. Do not cook it, which darkens the basil. Spread it on bread, stir it into minestrone, or drizzle it on tomatoes and mozzarella.

Substitutes

• Walnuts, almonds or cashews in place of pine nuts.
• Part arugula, spinach or parsley in place of some basil.
• For a dairy-free pesto, leave out the cheese and add a little more salt and nuts.

How to store it

Press plastic wrap on the surface or cover with a thin layer of oil, and keep it in the fridge for up to 5 days. Freeze it in ice cube trays for up to 3 months.

Common mistakes

• Letting it turn brown. Cut basil darkens as it meets air through oxidation. Some cooks blanch the leaves for 5 seconds and chill them in ice water to keep the color.
• Blending too long, which bruises the basil and turns the oil bitter.
• Using wet basil, which makes it watery.