in the world.

The original recipe calls for seven ingredients,

no more, no less.

Basil, extra-virgin olive oil,

pine nuts, Parmesan cheese,

pecorino cheese, salt, and garlic.

We are in Genoa, Italy.

Here is where pesto was invented.

And ask any Genoese you know,

and they will tell you that pesto made outside of the city

just can't compete with the one that is made here.

Why? Because all the seven ingredients here

are just a little bit more special.

Take the basil, for example.

This variety is considered the finest in the world

because it has smaller leaves than usual

and a more delicate flavor.

And just like basil,

all the seven ingredients are distinctly Genoese.

We're here to find out why.

Claudia: Once we've got our basil, we're at a crossroads:

mix the seven ingredients with the more traditional,

time-consuming pestle and mortar,

or use a more common mixer.

Both methods are possible and, most importantly,

accepted by pesto experts like Roberto.

Today, we'll see both methods,

because each one leads to a different-tasting pesto sauce.

Let's start with the more modern approach.

At the production site, the first thing that happens

is washing the leaves.

They are washed three times and disinfected

to lose all residues of dirt

and to make sure the leaves are absolutely clean.

Then they're dried.

Claudia: I think we got it by now:

Basil is an essential part of pesto.

About one-third of it, in fact.

Here, we just washed 5 kilos of basil,

which will make 15 kilos of pesto.

But what about the other six ingredients?

Unlike basil, not all of them come from Genoa

or its region, Liguria,

but they're all tied to its history.

We'll tell you more about them as they go in the mixer.

The first one to go in is extra-virgin olive oil.

Claudia: The second ingredient is the basil.

We now have the two cheeses, Parmesan and pecorino.

And when cheese is involved,

it wouldn't be a "Regional Eats" episode

without some tasting.

Unlike the basil and the olive oil,

these two cheeses are not local ingredients.

So how did they become part of the pesto recipe?

Well, the answer, at least for Parmesan, is simple.

The same way it is the king of cheeses

for 21st-century Italians, including me,

Parmesan held a special place in the hearts of Italians

and Genoveses in the Middle Ages.

Claudia: Back in the Middle Ages and until the 18th century,

notation was not the only thing happening in Genoa.

Genoa was also one of the most powerful trading cities

in the Mediterranean.

One of the main trade routes

of the Genovese maritime republic was Sardinia.

From there, sailors would bring building stones

back home to Genoa, but most of all --

and, I mean, can you blame them? --

pecorino cheese.

Claudia: We're getting to the end.

The fifth and six ingredients to go in for the mix

are pine nuts and garlic.

This garlic is a local variety called Vessalico,

named after a small town in this region.

It has a strong aroma

but a more delicate flavor than other varieties.

Claudia: Last but not least is a touch of coarse sea salt.

And, why not, a bit more olive oil.

Claudia: We've seen the more modern way to make pesto.

So now it's time to travel back in time

and familiarize ourselves with these two tools:

a wooden pestle and a marble mortar.

We'll do this in Roberto's restaurant, Il Genovese,

in the center of the city.

When making pesto with a pestle and mortar,

the order the ingredients go in is a little bit different.

Roberto starts with garlic.

Claudia: Now, it's the basil's turn.

Claudia: Sea salt.

We add the two cheeses and olive oil,

and our pesto is ready.

But we didn't taste it with pasta as promised, after all.