In Agatha Christie’s The Secret Adversary, Tommy lunches on “Sole à la Jeanette.” Poirot’s waistcoat is marred by “a morceau of filet de sole à la Jeannette” in The Mystery of the Blue Train. At a presentation recently, I mentioned that, while I have not found the exact recipe, I thought I had a good candidate. Someone in the audience suggested a specific website for further research.
Certainly, I had already spent a good deal of time poking around online, but I decided to look again. New information is being added all the time, so maybe I would find a different answer.
When I first started the research for Agatha Annotated, there was no Google AI Overview. Instead, the search engines would return a list of websites that matched my question in various ways. Sometimes those matches were really far-fetched, but they could be good starting points leading down a promising avenue.
Today’s AI Overview tallies up the most common matches and presents them as “facts,” even when the resources are questionable. Here’s Google’s response to a search for “Sole à la Jeanette:” “Culinary sleuths and retro-recipe enthusiasts trace the dish to classic Provençal cooking—specifically Filets de Sole Sauce Estragon (Filet of Sole with Tarragon Sauce) featuring butter, olive oil, and a rich, tarragon-infused sauce.”
I remembered the source Google’s AI Overview was referencing when I was looking a few years ago, the Poirot Blog by Kelly Klages. She has a 2018 entry on making a Poirot-inspired dinner, which includes Sole à la Jeanette. Klages, in turn, references a blog post from 2014 on a site called Reading Feeding.
The Reading Feeding blog wonders if Sole à la Jeanette is a real dish or something Christie made up. A commenter replies: “Actually a real dish made with a tarragon sauce. Jeanette Bertrandy – La bonne cuisine Provençal.”
Tarragon is not in the recipe I refer to in Agatha Annotated, and let me explain why.
La bonne cuisine Provençal is a cookery book written by Bernard Loubat and Jeanette Bertrandy. It was published in 1994, and Loubat passed away in 2025 at the age of 83. La bonne cuisine Provençal is described as “the culinary riches of yesterday and today that Provence is proud of.”
One of the recipes in the book is called Filets de Sole Sauce Estragon, or Filet of Sole in Tarragon Sauce. Loubat’s co-author was Jeanette Bertrandy. To me, that coincidence does not make this tarragon recipe the Sole à la Jeanette mentioned in Christie’s books.
In my research, I found a recipe for Fillets of Sea Bass, Jeannette Fashion, which seems a more likely candidate. Cooks might swap the sea bass for sole, but the sauce would be the same: butter, cream, egg yolks, and pureed clams. No tarragon. This recipe appears in The Post-Graduate Cookery Book, published in 1903.
The Secret Adversary was published in 1928, after The Post-Graduate Cookery Book and before Loubat was born. You know my theory. Now it’s your turn: Which recipe do you think Agatha Christie was thinking of? Tarragon or pureed clams?