Pesto Genovese: The Traditional Recipe

How To Make Pesto Genovese

Pesto Genovese is a raw sauce. Nothing is cooked, which means there is nowhere to hide: the sauce tastes exactly as good as the seven things you put in it. It takes about fifteen minutes, it is not difficult, and it dresses a pound of pasta for four.

The thing worth knowing before you start is that heat is the enemy. Bruised or warm basil turns black and bitter, and most disappointing homemade pesto is a temperature problem rather than an ingredient problem. Everything below is built around keeping things cold.

Equipment

8-cup food processor, the practical method
Mortar and pestle, the traditional method
Two-tone XL cutting board
Fine grater for the cheese
A bowl of ice water

Ingredients

These are the seven ingredients the Consorzio del Pesto Genovese recognises, in their proportions, converted to US measures.

4 cups fresh basil leaves, lightly packed, about 2 ounces
6 tablespoons Parmigiano Reggiano, finely grated
2 tablespoons Pecorino Fiore Sardo, finely grated
1 tablespoon pine nuts
2 garlic cloves
1/2 cup extra virgin olive oil
Coarse salt, to taste

A word about the garlic

Two cloves is the official proportion and it will look like too little. It is not, in Liguria. Genovese garlic is mild and sweet, and two cloves of it sit underneath the basil rather than on top of it.

Ordinary supermarket garlic is a different animal, and two cloves of a big aggressive head will run over everything else in the bowl. Start with one, taste, and add the second if it needs it. This is the single most common reason homemade pesto tastes harsh.

Choosing the ingredients

Basil is the one that matters most. Genovese basil DOP from Prà is the specified variety, small-leafed and sweet, without the aniseed edge that larger basil develops as it matures. If you cannot get it, use the youngest small leaves you can find and avoid anything with big tough leaves.

Pecorino Fiore Sardo is a Sardinian sheep's milk cheese, and it is the ingredient most often dropped from recipes outside Italy. It is worth finding, because it brings a sharp lanolin note that Parmigiano alone does not have. If you can only get one cheese, use all Parmigiano and cut the salt back, since Pecorino is saltier.

The oil should be mild. A grassy peppery Tuscan oil will fight the basil. Ligurian oil is specified precisely because it is delicate.

Method

Prepare

Chill everything. Put the food processor bowl and blade in the refrigerator for ten minutes before you start. Friction generates heat, heat oxidises basil, and oxidised basil goes brown. This one step does more for the colour of your pesto than anything else.

Wash and shock the basil. Rinse the leaves gently under cold water, then drop them into ice water for three or four minutes. Lift them out and dry them thoroughly, patting rather than spinning. Wet basil will not emulsify with the oil, and bruised basil is already browning before it reaches the bowl.

Grate the cheese finely. Fine grating matters here because the cheese has to disperse into a raw sauce with no heat to help it melt. Coarse shreds stay as shreds.

Make the sauce in the processor

Pulse the solids. Put the dried basil, both cheeses, the pine nuts, the garlic and a pinch of coarse salt into the cold bowl. Pulse in short bursts rather than running the motor. You are chopping, not blending, and continuous running heats the mixture and turns it dull.

Add the oil last and slowly. Once the solids are evenly chopped, add the oil in a thin stream, pulsing or stirring it through with a spoon. Adding oil at the start makes a thin sauce that separates; adding it at the end lets the mixture emulsify and hold together.

Rest before serving. Give it a few minutes for the flavours to come together, then taste for salt. Remember the cheeses have already brought their own.

The mortar, for anyone who wants the real thing

The word pesto comes from pestare, to pound, and the mortar is not nostalgia. A blade cuts the basil and releases its liquid; a pestle crushes and tears it, which extracts the aromatic oils differently and produces a sauce with a fuller texture and a rounder flavour. Marble and wood are traditional because neither conducts heat into the mixture.

Start with the garlic and a few grains of coarse salt, which acts as an abrasive, and work them to a paste. Add the pine nuts and crush them in. Then add the basil a small handful at a time, working the pestle in a circular grinding motion against the wall of the mortar rather than pounding straight down. Work the cheeses in, then dribble the oil in last, stirring.

It takes maybe ten minutes longer. Whether that is worth it is your call, and I would not tell anyone their processor pesto is not real pesto. But make it both ways once and you will taste the difference.

Serving

Never heat pesto. Cooking it kills the raw brightness that is the entire point and turns the basil dark.

Dress the pasta off the heat, loosening the sauce with a spoonful or two of the hot pasta cooking water until it coats rather than clumps. Trofie, trenette and linguine are the Ligurian choices. Boiling sliced potato and green beans along with the pasta is the classic Genoese way to serve it, and although neither is in the official sauce, they belong on the plate.

Variations

Walnut instead of pine nut. Swap the tablespoon of pine nuts for a tablespoon of walnuts. Walnuts are far cheaper and give a slightly tannic, earthier result. Toast them lightly first and remove any loose papery skin, which is where most of the bitterness sits. This is a traditional Ligurian move in its own right, not a compromise.

Dairy-free. Leave out both cheeses and add 2 tablespoons of nutritional yeast plus an extra tablespoon of nuts for body. Salt more assertively, because the cheeses were carrying most of it. It is not pesto Genovese any more, but it is a good basil sauce.

Pesto alla Trapanese. The Sicilian answer, from Trapani. Almonds instead of pine nuts, ripe raw tomatoes added to the basil, pecorino rather than Parmigiano, and no cooking. It is pink rather than green and it is excellent in late summer when tomatoes are worth eating.

Other greens. Arugula gives a peppery sauce that stands up to grilled meat. Kale needs blanching for thirty seconds first or it stays tough and raw-tasting. Carrot tops make a genuinely good pesto and cost nothing, which is the whole argument for them. In every case keep some basil in the mix, or you lose the perfume that makes this a pesto rather than a green paste.

Roasted red pepper. Roast and peel two red peppers, or use good jarred ones drained well, and work them in with the solids. This makes a sweeter, softer, brick-coloured sauce that is better on chicken and sandwiches than on pasta. Drain the peppers properly, because the extra water will thin the sauce and break the emulsion.

Make ahead, storage and keeping the colour

Pesto is at its best within an hour of being made. It keeps in the refrigerator for 3 to 4 days in an airtight container.

The surface will darken as it oxidises. A thin layer of olive oil poured over the top slows this down by keeping air off, which is standard practice. Two cautions with that. Keep it refrigerated, because a low-acid mixture containing raw garlic sealed under oil at room temperature is the exact set of conditions that produced documented botulism cases, which is why the FDA has required acidification in commercial garlic-in-oil products since the early 1990s. And do not leave it sitting out on the counter between meals.

Pesto freezes well, better than most raw sauces. Freeze it in an ice cube tray, then bag the cubes. Freeze it without the cheese if you are planning ahead properly, and stir the cheese in after thawing; the texture holds up noticeably better.

Where pesto comes from

The ancestor is Roman. Moretum was a paste of cheese, garlic and herbs pounded in a mortar, described in a poem traditionally attributed to Virgil. No basil, no pine nuts, but the same tool and the same idea.

The modern recipe appears in print in 1863, in Giovanni Battista Ratto's La Cuciniera Genovese. That is recent as these things go, more recent than the first tomato sauce recipe by nearly two centuries.

Since the 1990s the Consorzio del Pesto Genovese has worked to define and protect the traditional version, and today six of the seven ingredients carry DOP or IGP protection. Only the salt does not. Genoa holds a World Pesto Championship every two years, contested with mortars.

Nutrition estimate

Per serving, based on four servings of sauce and calculated from published values for the stated quantities: 320 calories, 33g fat, 6g saturated fat, 10mg cholesterol, 2g carbohydrate, 1g fiber, 0g sugar, 5g protein.

These are estimates rather than laboratory measurements, and they cover the sauce only, not the pasta. Salt is listed as to taste and carries no quantity, so sodium is not estimated here, though both cheeses contribute a meaningful amount.