Lemon Buttermilk Tart Frozen Yogurt, as all our frozen yogurts do, begins with Seven Stars Farm’s biodynamic organic yogurt. To that exquisite base, we add lemon juice and cream-thickened buttermilk. The result is a frozen yogurt with very rich body, a lovely creamy texture, and pronounced tart and tangy flavor. Pieces of savory, from-scratch shortbread crust made in house are added just before each batch goes into the freezer.