Pistou Provençal

The classic pesto alla genovese has spawned many an offspring, including Sicily's tomato-infused trapanese pesto, and scores of modern reinterpretations (arugula pesto, anyone?). Perhaps the one that resembles it the most in appearance and flavor is France's pistou, which comes from Provence and is typically stirred into a comforting summer soup. But pistou has key differences from its Ligurian cousin, and you may be glad to learn that those differences make pistou even easier and less expensive sauce to whip up.

Made from just four key ingredients—garlic, basil, olive oil, and salt—pistou has all the herbal aroma and allium punch of pesto, but usually doesn't include the cheese and pine nuts found in typical pesto. That makes it not only a simpler and more affordable sauce, but also one that works for vegans, those with nut allergies, and those who are cheese-averse.

In many recipes, a little something extra is stirred into pistou at the end. Sometimes it's a ladleful of the soup with which it's often served, but frequently it's a bit of fresh, finely diced tomato, which adds a sweet, fruity note that softens and rounds out the sauce; my recipe below calls for tomato.

I love any excuse to bust out my mortar and pestle, and this sauce is the perfect reason to do so. The crushing and grinding action of the pestle breaks open the cell structure of the garlic and basil, releasing more flavor and aroma than the chopping blades of a blender or food processor do, and the result is silkier—composed less of very finely minced bits and more of ultra-softened shreds. That said, the speed and convenience of a blender or food processor can't be denied, and good ones do an excellent job of producing a smooth and flavorful sauce. This recipe offers instructions for both methods.

One last note: If you want, you can pop the basil leaves into a freezer briefly before making the sauce, just long enough to turn them rigid. The ice crystals that form in the leaves break apart the cells, softening them before crushing or blending. At the same time, the cold temperatures temporarily deactivate browning enzymes that can cause the basil leaves to turn an unpleasant, drab color shortly after crushing or processing.

As for how to use the pistou, the possibilities are endless: in the classic soup; on toasts; on eggs; on sandwiches. It's particularly great on pasta or spooned over roasted or fried potatoes (or really on just about any starch). Put another way: Anywhere you might enjoy some pesto, pistou would be just as welcome.