I recommend you freeze pesto using an ice cube tray. Pour in your pesto dressing then once the cubes are frozen you can store them in a Ziploc bag. To freeze lemon basil salad dressing, spoon it into a jar and leave about ½ an inch of space at the top. Put a lid on the jar and freeze it. Once it's frozen, take off the lid and store the pesto in a plastic bag. When you're ready to use the pesto, thaw it in the refrigerator overnight. You can then use the pesto as you would any other pesto recipe.