From a Greek-American who made gyros at her church's Greek Festival just about every year since she was 15 (more than half her life):
* A gyro sandwich is pronounced YEE-row.
* The meat is a combinations of lamb & beef.
* Tzatziki is a cucumber/garlic/yogurt mixture.
* Would you like tomatoes, onions, lettuce with that?
Souvlaki is just lamb meat. Lamb is best right off the spit.
(Actually, in recent years, I've worked in the Greek Salad tent - much more easy going... load on the feta cheese please!)
Opa!