yogurt [optional]

Yogurt is a fermented dairy product produced by the bacterial acidification of milk, most commonly cow's milk, though varieties made from sheep, goat, buffalo, and plant-based milks also exist. The fermentation process involves introducing specific lactic acid bacteria—typically Lactobacillus bulgaricus and Streptococcus thermophilus—which convert lactose into lactic acid, creating the characteristic tangy flavor and thick texture. The resulting product ranges from thin, drinkable yogurts to thick, spoonable varieties depending on milk fat content, the fermentation duration, and the presence of added thickeners or stabilizers.

Different culinary traditions produce distinct styles: Greek yogurt (strained to remove whey, resulting in higher protein content), Icelandic skyr (technically a cheese but yogurt-like in texture), Middle Eastern labneh (further strained to create a spreadable consistency), and Indian dahi (traditionally fermented overnight in cloth). Flavoring varies from plain unsweetened varieties to those sweetened with fruit, honey, or added ingredients.

Yogurt functions across culinary roles as a condiment, marinade component, baking ingredient, and main dish element. In Mediterranean and Middle Eastern cuisines, it appears as a cooling accompaniment to spiced dishes, as a base for sauces (notably tzatziki), and as a marinade for meat. Indian cuisine incorporates yogurt into marinades (tandoori preparations), raita (cooling side dish), and as a leavening agent in baked goods. Yogurt's acidic nature tenderizes proteins and adds moisture to baked goods while its probiotic cultures aid digestive applications. It serves as a tangy substitute for sour cream or mayonnaise in many preparations and is essential in Middle Eastern meze platters.