Travelling, I only have a short recipe for you today. It’s from the Mondseer Kochbuch:
56 To prepare a good Lenten spoon dish (vasten muos)
Take basses and thick almond milk and put sugar on it. This is to be called “of Jerusalem” and it is eaten cold or hot.
Again, there is a parallen in the Buoch von guoter Spise:
62. A spoon dish (mus)
If you wish to prepare a good Lenten spoon dish (vastenmus), take basses and thick almond milk with them and boil them well in almond milk. Then put sugar on it. This dish (mus) is to be called “of Jerusalem”, and it is eaten hot or cold.
The combination of fish and almond milk with or without sugar is not uncommon for high-status Lenten foods. The only unusual thing here is the name, and I suspect there was something specific to this dish that made it “of Jerusalem” than just a fish mus. That need not have had anything to do with actual Middle Eastern cooking. Perhaps it was a certain manner of serving. I doubt we can reconstruct it.
The Mondseer Kochbuch is a recipe collection bound with a set of manuscript texts on grammar, dietetics, wine, and theology. There is a note inside that part of the book was completed in 1439 and, in a different place, that it was gifted to the abbot of the monastery at Mondsee (Austria). It is not certain whether the manuscript already included the recipes at that point, but it is likely. The entire codex was bound in leather in the second half of the fifteenth century, so at this point the recipe collection must have been part of it. The book was held at the monastery until it passed into the Vienna court library, now the national library of Austria, where it is now Cod 4995.
The collection shows clear parallels with the Buoch von guoter Spise. Many of its recipes are complex and call for expensive ingredients, and some give unusually precise quantities and measurements. It is edited in Doris Aichholzer’s “Wildu machen ayn guet essen…” Drei mittelhochdeutsche Kochbücher: Edition, Übersetzung, Quellenkommentar, Peter Lang, Berne et al. 1999