Starting today, I will go through a series of recipe sources I translated years ago and correct all the embarrassing errors I made. This is the first, a recipe collection fragment from the Teutonic Order.
[] Von Leberenne ein Gericht
A dish of liver
Take a liver and hard-boiled eggs, pound it in a stone mortar and mix it with good clear wine or with vinegar and this should be passed through (a cloth or sieve) or ground (in a handmill). And take onions and fry (sowdt) them in fat. This should be poured over fish or venison or meat, chicken, or whatever (else) you want.
The addition of hard-boiled eggs to a liver sauce is unusual, but the use of liver in this kind of dish is not. We should probably assume that spices go unmentioned since other such sauces always include them.
The Königsberg MS was preserved in the archive of the Teutonic Order in Königsberg (today Kaliningrad) in Baltic East Prussia, though its language suggests that it belongs to a Central or South German background. It is not associated with any name that I am aware of and is dated to the late 15th century purely on the scribal hand. The recipe types match South German sources of that time. It was published in Gollub (Hg.): Aus der Küche der deutschen Ordensritter. in: Prussia 31 (1935) pp. 118-124.