Should Pesto be Made in a Food Processor or Pestle and Mortar?

Short answer
While large-batch producers have no option but to use machinery, if you're making pesto at home, a pestle and mortar will make it taste infinitely better.

Long answer
We've conducted dozens of blind taste tests to determine whether pesto tastes better when made with a food processor or a pestle and mortar. The latter option has always won, and there are three very simple reasons why.

Heat is the enemy of pesto
Electric kitchen appliances generate heat, and the one thing you don't want to do to pesto is overheat it. If you do, you will destroy (or at least dull) all those wonderful fresh, herby flavours.

Crushing releases more flavour
Food processors and blenders use a crude method of breaking down ingredients. They effectively slice ingredients into smaller and smaller pieces. On the other hand, a pestle and mortar crushes the ingredients, releasing much more flavour in the process.

Fast blades turn olive oil bitter
The third reason you should shun a food processor or immersion blender is because the blade action of electric appliances shears olive oil into microscopic droplets. This causes the release of compounds called polyphenols, which will turn your oil, and therefore your whole sauce, bitter. Using a pestle and mortar doesn't do this.

Even if these rational arguments haven't convinced you to dust off your pestle and mortar, we can guarantee that your sauce will taste better simply because you've made it with your bare hands.