​ MORE OFTEN THAN NOT, holiday traditions are defined by what’s served, the food that becomes vetted and favorite for generations: Roast Turkey and dressing at Thanksgiving, Standing Beef Rib Roast or goose and Yorkshire pudding at Christmas. You get it—your family has its own, as does mine. Nancy Reagan’s Christmas tradition—one she’s served every year since she married, as her mother did before her—is all-American Persimmon Pudding with Hard Sauce. It’s this country’s answe