There are many misconceptions about the nature and preparation of the quintessential Greek fast food. Like many other famous Greek dishes, this was probably also originally Turkish and like many national dishes, what you find outside its country of origin bears little resemblance to the real thing. The souvlaki is essentially synonymous with the kebab and is known with a lot of similar names throughout the Balkans and the Middle East.

This is how the real Greek souvlaki works, whether being consumed by a visitor to Greece or a fan of ethnic food elsewhere in the world, as compiled by a former long-time resident of Athens:

  1. Let's start with the distinction between the gyros and the souvlaki. Asking for a "souvlaki" will normally result in a kebab--meat on a skewer, especially outside Athens. The distinction is hazy even within its countries of origin and may vary from area to area, so for the purposes of this document we'll consider souvlaki to be a generic term that includes both the kebab and the doner/gyros, though strictly speaking it's only the former.
  2. The classic "souvlaki" known throughout the world is purchased by asking for "gyro pita" (YEE-roh PEE-tah) Note that the "pita" is essential to denote the wrap, asking for "gyro" will likely get you the full monty--a "merida" (portion) twice the size of what you can eat, similar to what you'll find calling itself gyros in quasi-Mediterranean restaurants abroad. On the other hand, a "souvlaki (me) pita" would be a classic souvlaki with meat from a skewer in it instead of meat sliced off the big spit.
  3. A "doner" is another name for "gyros" (the Turkish and/or Arabic original) and a term more widely used in the city centre rather than in the neighbourhood "souvlatzidiko."
  4. Fancier souvlakia (kebabs) may come with pieces of onion and green bell pepper between the pieces of meat.
  5. Chicken souvlakia are increasingly common and many shops now carry them. Some shops have a separate spit for chicken but I'd go for the souvlaki instead, the meat on the spit tends to be of lesser quality.
  6. There have been reports of people selling souvlaki sandwiches. Any professional who calls it a "souvlaki sandwich" ought to be condemned to a year of flipping burgers at McDonalds. I've never heard of it, it's probably strictly a tourist trap term and would make any Greek look at you funny. If you're offered a souvlaki sandwich, it's something totally different.
  7. Many places in the centre have blackboards with the menu written on them outside the shop, usually in awful but recognisable transliterations.
  8. Sitting at a table is an implied invitation to be served a full meal. Go stand in line.
  9. Some places will lace the onion with parsley to draw out the bitter flavour of onion that's been cut for a while (great cooking tip). Others will combine it with lettuce.
  10. The meat in the gyros is commonly a blend of pork and lamb (or mystery meat). Definitely not kosher. If you're Jewish or Muslim, you'll want to avoid it and go for the souvlaki (kebab), which is usually lamb (see 2).
  11. Tzatziki is meant to have the consistency of yoghurt. The only thing dripping out of the bottom of a wrap should be grease, not runny tzatziki.
  12. Good tzatziki contains garlic... in quantities. Beware!
  13. Putting ketchup and/or mustard in a souvlaki is criminal. Yet there are shops that do it. Watch closely if you see ketchup and mustard standing near the preparation area.
  14. If asked "ap'ola" or "komble," they want to know whether they should hold anything. Say "horis kremmydi" to get one with no onion and "horis tzatziki" to skip the tzatziki, though why you'd do such a thing is a mystery.
  15. Enjoy.

[Adapted from the web for E2--I'm plagiarising only myself]