This excellent French recipe calls for an exotic ingredient: walnut wine (vin de noix). I like to make my own and offer a recipe for it in The Cooking of Southwest France revised edition (2007). But it does require access to a walnut tree and a year and a half of aging. If you wish to make this recipe in a timelier fashion, I suggest substituting the Italian green walnut liqueur nocino or a mix of good red wine with a little port wine or