Tip from Enrica Monzani of A Small Kitchen in Genoa

In the process of making Genovese basil pesto, I think the most important tip for the flavor is to remove the stems from the leaves, because the stem is bitter and watery and it really changes the flavor of your pesto. Also, the best basil is young basil. I know it's difficult to find a basil as mild and tender as ours outside the Ligurian border, but look for the smallest, brightest green leaves for making pesto. It will be less bitter and have less of a minty taste at the end.

For the nuts, we use just pine nuts. The best are Italian pine nuts, which are quite expensive, or, if they are not available, walnuts. No cashews and no other nuts. Better walnuts than Chinese or Turkish pine nuts.

Pesto is a cold sauce, so you never toss pasta al pesto in a pan before serving. When you have made pesto, always dilute it with some of the pasta's boiling water, then mix quickly so the starch in the water emulsifies with the oil in your pesto and makes it very creamy. Then you season the pasta with the pesto. The same goes for pesto from a jar: always dilute it with some pasta water.

When we make pasta with pesto, we usually also add diced potatoes and green beans to the boiling pasta. Then you drain the pasta and vegetables and season them with the pesto. It's an old trick of poor people to stretch the dish and make bigger portions, because pasta was very expensive.