The freezer can be a powerful, overlooked method of preserving. Freezing herbs in oil reduces part of the browning and freezer burn that herbs can get when frozen. It's also a great way to have herbs immediately ready for stews, roasts, soups, and potato dishes. These dishes usually call for oil to start with, and so you can take a cube of frozen oil, herbs inside, out of the freezer and use this as the base of your dish. Cook your onions & garlic in this herb-infused oil and let the taste of herbs spread through your whole dish. Yum!
Keep in mind, the oil-and-freezer method of preservation works best with the tougher hard herbs such as rosemary, sage, thyme, and oregano. These are all herbs that would probably be cooked when added to a dish. Soft herbs such as mint, basil, lemon verbena, and dill are usually added raw to a dish, and they don't respond as well to this kind of preserving.
Here are some tips on preserving herbs in oil.
8 Steps for Freezing Herbs in Oil
Choose firm, fresh herbs, ideally from the market or your own garden.
If you wish, you can chop them fine. Or leave them in larger sprigs and leaves. Here I froze a combination of finely-chopped and whole herbs such as rosemary, fennel stalk, sage, and oregano.
Pack the wells of ice cube trays about 2/3 full of herbs.
You can mix up the herbs, too; think about freezing a bouquet garni of sage, thyme, and rosemary to add to winter roast chickens and potatoes!
Pour extra-virgin olive oil or melted, unsalted butter over the herbs.
Cover lightly with plastic wrap and freeze overnight.
Remove the frozen cubes and store in freezer containers or small bags.
Don't forget to label each container or bag with the type of herb (and oil) inside!