In the children’s book Strega Nona, a village herbalist in Calabria owns a magic pot that can produce an endless flow of delicious pasta. Her boarder, a bumbling oaf named Big Anthony, tries to use the pot while she is away, bringing disaster. His mistake? He didn’t know to blow three kisses after chanting the magic spell.

Spoken about in whispers, guarded by barchans, bubbles and bibs the world over, culinary secrets—most often ingredients—are handed down with ritualistic seriousness, like cast-iron pans. And yet these secrets often turn out to be quite ordinary: a pinch of pepper in the strawberry pie, a touch of sugar in the ragù, a dash of plum vinegar in the pot roast. And yet we obsess, arguing beyond reason that our family’s sweet potato pie is like no other, or rushi...