Cover tightly and refrigerate at least 30 minutes to allow flavors to blend. See note below.
[[Modified from a recipe from the California Table Grape Commission, although I'm not seeing it on their current website.]]
Best to make this the morning of rather than the day before. It will keep in the refrigertor for a few days, but the avocados will turn this into a still-tasty albeit grayish, slimy mass pretty quickly.