I've been wending my way through Vincent Price's TREASURY OF GREAT RECIPES, written with his then-wife Mary and published in 1965. It's quite amusing and eccentric, with some totally authentic recipes from Western Europe, Mexico, and all around the U.S. It's much more available than a lot of cookbooks from the era. I found it at the Strand after a recommendation from the impeccable SAVEUR a few years ago. The book is organized by country and (roughly) by then-leading restaurants, with some campy color photos and period menus, and Vincent's headnotes to recipes are most amusing and cordial.
Anyway--a Spanish recipe for "Pork Cutlets Escorial" calls for "6 tablespoons finely chopped mustard fruits in their syrup." I have never heard of mustard fruits. Are they a relic of the 1960s never to be found again?