Add all ingredients in a large blender or food processor. Puree until completely smooth, about 1-2 minutes depending on the power of your blender. (You may have to do this in two batches if your blender isn't large enough.)
Taste and season with more salt if necessary.
Transfer to a large glass container, cover and refrigerate for at least 4 hours or up to overnight to help all the flavors meld together.
Serve cold with croutons, cilantro and a drizzle of olive oil.