This is an excerpt from Libre del Coch
(Spain, 1520 - Robin Carroll-Mann, trans.)
The original source can be found at
Mark S. Harris' Florilegium
180. OF lamprey in crust. The lamprey needs to be alive, and scald it with hot water, and in this way you will make it clean and white, and then take toasted bread, so much so that it is all black, and grate off the burnt part. And take the lamprey and open it. And catch that blood and keep it, and remove from it the intestine that it has. And through the mouth pierce it with a knife in such a manner that you do not cut it at all, but only prick it, and remove the bile by means of the head. And leave it so that this blood strains out well, and similarly strain the blood from the holes that the lamprey has, and carefully keep all the blood, and anoint it completely with its own blood. And then take your spices which are long pepper, and galingale, and nutmeg. And all this should be well-ground and mixed with that blood. And then return to anointing the lamprey with it. And put a nutmeg in the mouth. And place a clove of gilofre inside each hole that it has. And then take the lamprey, and put it in a empanada in the form of a rosca. And give it a cut in the center of the spine, because otherwise it could break the empanada. And being put in your empanada, well anointed with its own blood, with the spices and everything, cover the empanada. And cook it in the oven. And then take toasted bread with vinegar and red wine and its own remaining blood. And mix everything together, and strain it very well. And this sauce should not be very sour, but only a little, and for this one puts in the wine. And when the empanada is cooked, take this sauce and cast it into the empanada. And these empanadas of lampreys are better eaten cold rather than hot. And if it is cold, do not cast sauce on it. And the lampreys are not good to eat until the month of January.