Quark is a fresh, soft, acid-set curd cheese — smooth, white and mildly tangy — that sits somewhere between yogurt, cottage cheese and cream cheese. It is a daily staple of German, Austrian and Central and Eastern European kitchens, spread on bread with herbs, stirred into cheesecakes and dumplings, whisked into fruit desserts, or eaten plain as a high-protein, low-fat dairy that spoons like thick yogurt.