Another illusion food from the Innsbruck MS. This one really makes no practical sense at all.
57 If you would make rice out of eggs, boil the eggs hard and then take the hard egg (daz hert) and chop it very small. Take good milk and boil the (cooked) white in that, and if you wish, take egg white and a little fine flour and beat that together. Pour it into the pot that has the rice in it. Thus it will become thick. Do not oversalt it.
The recipe itself is neither complicated not implausible. It is easy to see how one would do it, but not so much why. Many surviving recipes for illusion food are intended for Lent, a way of simulating meat, dairy and eggs on days when they were prohibited. Others are complex and playful, cooking chickens in jars or preparing large fish to appear cooked in different ways along their body. This is just mashed and cooked eggs to mimic rice cooked to a mush. This, incidentally, was how Europeans prepared rice at the time. Cooking it to keep the grains separate, as was the custom in the Ottoman Empire, was uncommon and worthy of note. Rice, of course, was never prohibited, and though dairy was on certain days, this dish does not substitute the milk. It really looks as though whoever came up with this just liked playing with food.
The Innsbrucker Rezeptbuch is a manuscript recipe collection from a South German/Austrian context. It dates to the mid-fifteenth century and survives as part of a set of medical and culinary texts bound together. The editor Doris Aichholzer published it together with two related manuscripts and drew attention to the less elaborate, more practical recipes. The manuscript is of unknown provenance, but has been owned by the Habsburg emperors since at least the early sixteenth century. It is now held at the Nationalbibliothek in Vienna. An edition, German translation and commentary can be found in Doris Aichholzer: Wildu machen ayn guet essen… Drei mittelhochdeutsche Kochbücher, Peter Lang Verlag Berne et al. 1999