Popovers are the hollowest of muffins. The perfect bread-form soup spoons, or whipped cream receptacles. They look like a herd of mollusks perched on the cooling rack. I’ve made these before, to the smooth tones of Teddy Pendergrass crooning on about hot oils (key ingredient, here)—but never with sourdough starter, which is this month’s Sourdough […]