The version I’ve been eating for a couple of decades goes like this:

Good bread is key, I like olive sourdough or something chewy with grain. Layer of avocado, layer of hummus, sprinkle feta cheese, sliced tomatoes, lettuce on the side as a “chaser” and... yum.

I guess that’s “cultural” in that it’s just adding avocado to a Greek thing. I’d guess that’s the story of how a lot of people got into various new produce... add it to the familiar.