I have been making celery root mashed potatoes for Thanksgiving since I was 14 years old. I got the recipe from a French women’s magazine that my sister sent to me from her year abroad at the Sorbonne. As a young Francophile studying French, that magazine was a worldly treasure. I pored over every page, obsessing over details like how Parisian women tied their silk scarves — and how they cooked chic recipes.