This recipe is very interesting, not least because of its parallels, and because it suggests my interpretation actually was correct. They ate fish jam.
40 If you would make a good galantine (galrad) of a pike, boil the pike and chop the flesh. Then boil the flesh in wine and honey and turmeric (gelbwurtz). Boil this together until it can be poured like an electuary (latwargen) and do not oversalt it.
This recipe is for a galrad, a word that can refer to various kinds of preparation ranging from aspics to thick spicy sauces and a kind of pickle. Here, it seems to mean a mixture of fish and honey cooked down to a thick mush. Electuaries (latwargen), the reference point for thickness, were typically cooked from mashed fruit, sugar, or honey until they firmed up when cool. They were used as the basis for sauces as well as being eaten in dessert courses. How the category of galrad can encompass what is basically a fish jam, or in what context this would have been eaten, I cannot say.
Now, there are several recipes in other sources that I have already written about and even tried out with a modicum of success. I felt uncertain about the interpretation because though the recipe occurs in three sources, it is clearly copied from the same original text. However, the entry in the Innsbruck MS, while describing a very similar dish, is not drawing on the same source as we can see when we compare it to Cod Pal Germ 551:
23 Galantine (galreit) of fish
If you would make galantine of fish of a pike, boil the pike nicely and take off its flesh (prat). Then take honey and set it over the coals and let it boil and take the flesh of the pike and pepper and sugar enough and stir it together, neither too thin nor too thick, so that it can be poured onto a bowl like an electuary. And do not oversalt it.
Clearly, this is a real dish, not some copyist’s mistake or misinterpretation. It will take some playing around with the preparation to see whether it produces something palatable.
The other interesting aspect to the recipe in the Innsbruck MS, one that is not shared with the parallels, is the use of gelbwurtz. The word is reasonably familiar by the fifteenth century from technical literature, usually in the context of dyeing or painting. It refers to turmeric (Curcuma longa), not, as it does today, Xanthoriza simplicissima, which is American in origin. As far as I know, this is the first mention of it in a culinary context anywhere in the German corpus, and it remains quite unusual for a long time. Yellow colouring is usually achieved with the more expensive saffron. It does, however, raise the question whether the ubiquitous single-verb imperative to “colour it yellow” (gilbs) left the choice at the cook’s discretion.