Kefir
A fermented milk drink made with kefir grains, a culture of bacteria and yeasts. It is thinner than yogurt, tangier, and slightly effervescent.
Eastern Europe
Across Eastern Europe, cultured dairy is a daily staple: kefir, ryazhenka from baked milk, and smetana, the region's cultured cream.
Ryazhenka
A cultured milk from Eastern Europe made from baked milk: milk held at low heat for hours until creamy and caramel-tinted, then fermented. It tastes like a mild, toasted yogurt.
Smetana
The sour cream of Central and Eastern Europe, cultured cream with a clean tang and a thick, spoonable body, usually around 20 to 30 percent fat in commercial versions.