Greek salad may be a single most famous Greek dish. I knew it far before I travelled and lived in Greece, as you can find it on the menu in almost any restaurant. As I grew to be a cook, an important thing I learned about dishes that are almost like a cultural trademark is that every ingredient counts. Salad will taste differently in Serbia, Japan and totally differently in its birth land. With that in mind, we can get away from using Greek vegetables as they are rarely available except for the neighbouring countries, vinegar or spices (though Greek oregano and vinegar make a huge difference in taste), but one cannot make Greek salad with anything but Greek feta and olive oil. Feta is by far the most famous Greek brine cheese that has been made for generations from 17th century by certain procedures pasturing in certain conditions and only from 70% or more goat and sheep milk and never from cow milk and it is a product of protected designation of origin (PDO)* . This means that cheese from any other country cannot be called “feta”. “Horiatiki”, as Greeks call this salad means village salad, and probably the most original is the way the cheese is served- a whole uncut slice on the top of it.  

*The European Commission has instituted the protection of the geographical origin of various products, through their characterisation as products of Protected Designation of Origin (PDO).