M.F.K. Fisher, known to friends and family members as Mary Frances, boasted that she wrote her books in “invisible ink” and that she had “invisible maps” of places where she had made her home, like Aix-en-Provence. I didn’t catch up with her until she settled in Glen Ellen, California, an invisible town, until folks like Jack London and, much later, gonzo journalist Hunter S. Thompson found that it suited their fugitive ways. Mary Frances wasn’t a fugitive from the law, but she maintained a very low profile in Glen Ellen, where she hosted intimate gatherings where she served champagne, real champagne from France, and oysters from Hog Island on the Sonoma Coast, an hour’s drive away. I’ve long loved the idea of writing in invisible ink and consulting invisible maps; they appeal to my underground self, the self that wants to be in hiding and only surface on rare occasions. Mary Frances might have written her books — Consider the Oyster, How to Cook a Wolf, and The Gastronomical Me — in …