Many culinary herbs love cool weather — and when summer hits, they bolt (go to seed) or get tough and lose their delicate flavor. That’s why early summer is the best time to start preserving herbs for later use.
There are lots of ways to preserve herbs, including drying and freezing, but my favorite methods are to make compound butters and pestos. All are easy and take less than an hour, from cutting the herbs to cleaning up. But the rewards are big — allowing you to dress up plain meat, fish, vegetables, breads, sandwiches, and pasta later with virtually no effort.
I like to begin by thinking back to my favorite recipes that call for fresh herbs, then concocting either a butter or oil-based pesto to contain the flavor. For example, I often make a fish soup that calls for fresh dill, which is not easy to find at the time of year when I want to eat hot soups. A few pats of dill butter from the freezer provide the flavor without a trip to the store. Similarly, if I’m making a dish that calls for fresh cilantro, it’s nice to have an oil-based cilantro pesto in the freezer.
To make compound butters, let butter soften to room temperature. Chop herbs very fine, or pulse in a food processor. Use about 3 Tablespoons of herbs per stick of butter. Add salt to taste if using unsalted butter. You can also add minced garlic or shallots if you wish. Stir into the softened butter until well combined. Roll the herb butter into a loaf shape, and wrap tightly with aluminum foil, wax paper, or plastic wrap. Label the roll-up, place in an airtight container and freeze.
I have some rectangular glass containers with plastic lids that are perfect for storing several herb logs. To use, I grab the flavor I want, slice off a tablespoon or two, rewrap, and return to the freezer.
The most useful spring herbs for butters: chives, dill, fennel, and parsley. Later in the season, you can make compound butters with summer herbs including thyme, rosemary, oregano, marjoram, and mint. And of course you can mix several types of herbs for your own signature compound butter or to use up produce you have at hand such as garlic and shallots.
Pesto made with basil is essential to every Italian kitchen, so you probably know how to make it. The same recipe you use for basil pesto can be adopted to other leafy herbs including arugula, cilantro, mint, and parsley. When making herb pesto for the freezer, skip the cheese but otherwise follow your favorite pesto recipe.
A general guideline for proportions is to use 2 cups packed leaves, pulsed in a food processor with or without nuts and garlic. With the processor running, drizzle in a half cup of olive oil and process until smooth. Season with salt and pepper to taste.
Spoon the pesto into ice cube trays, then top each cube with a film of olive oil to preserve the color. Freeze, then transfer the cubes to an airtight container for long-term freezer storage.