Combine. Place all ingredients in a blender or food processor.
Puree the sauce until very smooth. You may have to scrape down the sides a few times, but it should get very smooth, light, and airy.
Taste & Adjust. Taste the sauce and add additional, salt, pepper, cilantro, or citrus juice, to taste. (Keep in mind the flavor will continue to develop with time!)
Thin, If Desired. 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.
Serve & Store. Enjoy on tacos, taco salad, burrito bowls, sandwiches, burgers, grilled chicken, and more! Leftover citrus avocado sauce will keep 3-4 days in the refrigerator, or can be frozen for 1-2 months in an airtight container.