Place all ingredients in a blender or food processor and puree until very smooth. You may have to scrape down the sides a few times, but it should get very smooth, light, and airy. Taste and add additional salt or pepper, as needed.To use as a salad dressing, add 1 tablespoon of water at a time to the dressing and whisk or blend to incorporate well, until you've got it as thin as you like.This will keep 3-4 days in the refrigerator, or can be frozen for 1-2 months in an airtight container. To use, simply thaw in your refrigerator or a bowl of cold water. Whisk to bring everything back together and serve cold!