Now this one clearly is a jelly
1.vii Item to prepare jellied fish (gesultz visch) in summer where they do not gel readily. As you prepare the fish, keep the blood and the scales and bones. Put that into a pot and boil it with wine. Skim it well and pour it into a mortar. Pound it well and pass it through a cloth with its own broth in which it has boiled. A bay leaf is ground and passed through with it, that way it will gel. Lay the fish into as many dishes as you wish to make when they are already boiled. Then take the fish broth, add the broth of the scales together with spices and all (needed) things. Try (to see) what it lacks in flavour of vinegar, salt or spices. Let it boil up in a pan one time and then pour it over the fish. Then let them cool in an airy place and then store them (? setze sie dan ein).
If you would strew almonds or raisins on them, do it timely before it has half gelled. That way they, too, remain nice and clean.
And of course it is called gesultz which just proves as far as German recipe writers are concerned, semantic consistency is something that happens to other people.
My current project are recipes from the Nuremberg Kuchenmaistrey produced around 1490. This was the earliest printed cookbook in German (and only missed being the earliest printed cookbook in any language by a few years). The Kuchenmaistrey (mastery of the kitchen) gave rise to a vibrant culture of amended and expanded manuscript copies as well as reprints spanning almost a century. The recipes seem designed to appeal to a wealthy, literate and cosmopolitan clientele.