This recipe from the Mondseer Kochbuch is familiar from many other sources, but is more detailed than most:
112 A pike that is boiled in the middle and roasted at either end
Take a white cloth that is one hand wide or wider and moisten it with wine. Take out the stomach and the liver so the stomach stays whole. Take a piece of another pike and fill the stomach with it. Add fat and let the liver and the stomach boil until they are done, (but) so that the liver stays whole. Fill the pike again so the liver and the stomach stay together in the middle of the pike. Take the cloth and moisten it, and it must be long enough to go around twice. Wrap it around the pike. When you have wrapped it around, wrap it around again (with a second cloth). Salt it and wrap the cloth over the salt, and season the pike all over the back and all around. It should be salted on bopth ends all around (and) between the two cloths. How take a thread and wind it around and around. The cloth must be fourfold. Take and scale (the fish) at both ends. When you wish to roast it, take a spit and thrust it through the cloth, thus it stays more whole (gantzer). Salt it like a roast fish and take two bricks, lay them at the corners (of the fireplace) and lay the spit on them and roast it like any other fish. Put good fire under the cloth, but a small fire under the other parts. And you shall take broth. Where you wish to boil the pike, you shall pour that over the cloth so it does not burn. That way the fish boils under the cloth (in der pinten). And you shall take small pebbles that are hot and stick them under the cloth and pour hot broth over the cloth. Thus it runs over the stones and the pike boils nicely. Just roast it properly.
113 To prepare two sauces and a soup for the pike
With the tail, prepare a green sauce. Pass it through with vinegar, thus it becomes sharp, and add spices to it. For the head, take a fierdung of raisins and half a fierdung of almonds, and skin those nicely. Pound the almonds and raisins together.
If you wish to have a good sauce, pass the herbs and the bread through a cloth with rainfal (Ribolla gialla wine) or rumenier (Romania wine). Add good spices and sugar to it, thus you have a good sauce.
The underlying recipe here is for preparing a single, large fish so that different sections are cooked in different styles, typically one roasted, one boiled or steamed, and one fried. We have numerous recipes for this from various sources and the process seems to go back to Abbasid Baghdad where it is recorded in the recipebook of ibn Sayyar al Warraq (chapter 33, recipe 5). Surviving German recipes often differ in detail, sometimes cutting apart the fish and reassembling it, but the most impressive display of skill lay in keeping it whole, as this iteration does.
The instructions we are getting here mainly focus on the way of preparing the middle part which is boiled (or rather steamed) under a wet cloth. The front and rear parts are not treated in any detail, but we learn in a different recipe that one section would be roasted dry, the other dusted with flour and basted with fat. All of it would make a showy dish served with various sauces to accompany each part. It probably does not need saying that between calling for fresh pike and the most expensive wines, expending a vast amount of skilled labour, and probably ruining a perfectly good length of linen, this recipe represents a level of luxury bordering on decadence.
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