On a hot June day, I open the freezer in my mother's kitchen looking for a tray of ice. Instead of clear, slippery cubes, I find green, coarse ones. Although I am eight years old, I am puzzled how the cubes changed color and texture overnight.
At dinner that evening, my mother brings out a plate of steaming pasta the same verdant shade as the cubes. Like many cooks, she makes batches of pesto when basil is in abundance during the summer, storing and freezing them in ice trays and transferring them to Ziploc bags for use during the fall and winter. And so began my love affair with pesto.
Originally from Genoa, Italy, this sauce is traditionally made from fresh basil, toasted pine nuts, garlic cloves, and grated parmesan cheese, pounded together and diluted with fine olive oil that is not too strong in flavor.
The pesto I enjoy today is a different than my mother’s basil-centric versions. A quick internet search yields intriguing combinations: ginger and black sesame pesto, arugula and cashew pesto, and even chocolate mint pesto. (For the curious cooks out there, this dessert pesto, which is spread in between wafers, is made from chocolate mint, a type of mint leaf that smells like a York peppermint patty; stevia, an herb whose leaves have a granular crunch and taste like sugar in the raw; macadamia nuts; walnut and hazelnut oils, and splash of rose water).
Even more exciting than the new flavor profiles are the creative ways to utilize this sauce. Besides traditionally accompanying pasta, pesto can be found in salad dressings and soups, and as marinades or toppings for vegetables, fish, chicken, pizza, and fondues. Those who are lactose intolerant, or kosher cooks who prefer serving pesto with a meat meal, can easily leave out the cheese. Using more than one type of herb and a mixture of nuts produces a complex sauce whose absence of cheese will be hard to detect.
A debate ensues amongst cooks whether pesto is best made with a food processor or a mortar and pestle. Hand-grinding releases more of the essential oils without cutting through the cell walls of the ingredients, yielding a silky, shiny texture with a refined flavor. A food processor, while an obvious time-saver, creates a pesto where the oils are not as intensely released because the cell walls of the ingredients are cut through. While the texture is more uniform, the flavor may be too sharp and unbalanced.
Regardless of the equipment or the specific flavor profiles, the most important aspect of an excellent pesto is to use good quality ingredients. Make sure the herbs are fresh, the nuts toasty, and the oil clean. When combined, these ingredients will elevate any dish they accompany.
Here’s what you need to know when choosing ingredients for a fabulous pesto that will leave your taste buds wanting more.
Herbs—Always use freshly picked herbs to ensure the highest quality taste. To prepare the herbs, remove the stems and lightly pack the leaves in a measuring cup until the desired amount is reached. Immerse the leaves in cold water and use your fingers to wipe away residue. Shake off the water and roll the leaves in a paper towel or dry in a salad spinner.
Garlic—Never substitute garlic powder for fresh cloves or the taste and consistency will suffer.
Cheese—If you can, freshly grate cheese to ensure the pesto will have a full cheese flavor. Once the herbs, nuts, garlic and oil are combined, add the grated cheese by hand so the flavor will be balanced.
Oil—When using olive oil, choose an extra-virgin oil that tastes of olives and doesn’t have a strong aftertaste. If milder nuts and herbs are used, experiment with oils such as corn, canola, safflower or walnut which may provide a more neutral taste.
Nuts—While nuts can be added raw, toasting them releases essential oils and creates a more intense flavor. Walnuts are often used in stronger pestos and milder nuts such as pine nuts, unsalted pistachios, or almonds are used in delicate pestos. For those with nut allergies, or if you want to make your pesto a little different; olives, capers, and sun-dried tomatoes make good substitutes.
Storage—For long term storage, pack the pesto into small containers, cover with a thin layer of olive oil and cap tightly to seal in the flavor and to avoid oxidation. Exclude as much air as possible to prevent loss of color and moisture.
When preparing pesto that will be frozen, make sure the herbs are completely dry before adding the rest of the ingredients. If water is left on the leaves, ice crystals will form once the pesto is frozen, weakening the flavor and texture.
Pesto freezes best when there is slightly more oil in the mix because the fat protects the herbs from potential freezer burn. If you intend to freeze the pesto from the start, add a few tablespoons oil or softened butter or margarine.