Tzatziki, tzadziki, or tsatsiki (Greek: τζατζίκι) is a Greek meze or appetizer, also used as a sauce for souvlaki and gyros. Tzatziki is made of strained yoghurt (usually sheep's-milk or goat's-milk in Greece and Turkey) with cucumbers, garlic, salt, usually olive oil, pepper, dill, sometimes lemon juice and parsley, or mint added. The cucumbers are either pureed and strained, or seeded and finely diced.
Olive oil, olives, and herbs are often used as garnishes. In Cyprus, the dish is known colloquially as ttalattouri (cf. tarator), and recipes often include less garlic and includes the herb mint, unlike the Greek counterpart.
Tzatziki is always served cold. In touristy restaurants, and outside Greece and Cyprus, tzatziki is often served with bread (loaf or pita) as part of the first course of a meal. Greeks, Cypriots and those from all over the Middle East use this dish as a side dish to a meal with meat.
The acidity cuts the fat, thus tzatziki is also used as a sauce for souvlaki and gyros, in which case it may be called cucumber sauce (especially in the U.S.). The Greek word is derived from the Turkish cacık, which means a form of chutney (cacık, the Turkish side dish with similar ingredients, is diluted).