When I pull tender leaves of basil from their stems, I can’t resist closing my eyes and taking a deep breath; the fragrance is pure summer. One of my favorite ways to showcase the herb is to make a traditional Genovese pesto sauce, a purée of lots and lots of basil with garlic, pine nuts, cheese, and olive oil. Not only is this potent sauce versatile—equally at home on pasta, in an omelet, and paired with chicken—but because I can freeze it, I can make pesto when basil is at its best and then continue to enjoy it through the fall.
A blanching and a blender give you the best results
Most cooks agree about the ingredients that go into traditional pesto. What we don’t often agree on is the best way to combine these ingredients. As its name implies, pesto is traditionally made using a-mortar and pestle. Although some swear that pounding gives you the best flavor, I’ve never noticed a difference that’s worth the effort. Others prefer to use a food processor, but while this machine certainly speeds up the process, the ingredients tend to bounce around and fly onto the sides of the bowl, resulting in an inconsistent texture. I prefer to use a blender. Because of the blender’s tapered shape, the ingredients are drawn to the blade, where they get puréed more evenly. I’ve noticed with some blender models, however, that you’ll have to help the puréeing along by periodically stopping the motor and moving the ingredients around with a spatula or a spoon.
Robert Danhi prefers a blender for making pesto. The action of a blender pulls the ingredients into the blade, whereas food processors spray a good portion of the ingredients against the sides fo the bowl.
Check for a coarse purée before adding the oil. You may need to stop and start your blender at first, as well as scrape down the sides.
A quick blanch before blending softens the basil, creating a more supple sauce. There are two reasons why I blanch my basil before puréeing it. One of them, admittedly, is purely cosmetic: a brighter green color that holds for several days. More important, however, is the texture. Blanched basil emulsifies more easily to produce a smoother yet full-bodied sauce. Blanching will slightly reduce the potency of the fresh basil flavor, but because a good bunch of basil starts out so incredibly fragrant, the reduction is minimal. Just be sure to dip the leaves only briefly in the boiling water and then quickly plunge them in ice water to keep them from overcooking.
The briefest dunk is all you need. You want the leaves to become limp but not cooked—just a few seconds in the hot water.
A shock in ice water stops the cooking and keeps the color. This blanching step makes the pesto super-creamy and helps it stay emulsified.