The main ingredient in the traditional Greek dish tzatziki is yogurt. Specifically, it is made from strained Greek yogurt, which gives the dish its rich, creamy texture. Tzatziki is typically mixed with cucumbers, garlic, olive oil, lemon juice, and fresh herbs like dill or mint. This refreshing sauce is commonly served as a dip alongside pita bread, grilled meats, or as a condiment in various dishes. It is particularly popular in Mediterranean cuisine and often accompanies Greek meals, adding flavor and creaminess.