📷 Closely related photo — Photo: tomislavmedak / Flickr · CC BY 2.0
The word ayran is Turkish, and the drink is close kin to Iran's doogh and South Asia's salted lassi, all built on yogurt, water and salt.
Plain yogurt is thinned with cold water and salt, shaken until frothy, and poured over ice. Beirut's street carts, especially near grill and shawarma stands, sell it in tall cups as the go-to wash-down for something rich and salty.
Why it's made this way: The drink's name and technique arrived with the same Ottoman and Armenian influences that shaped Beirut's grilled-meat street food, and it's now the default order alongside a soujok or shawarma sandwich.