This is an excerpt from Du fait de cuisine
(France, 1420 - Elizabeth Cook, trans.)
The original source can be found at David Friedman's website
4. Again, a lamprey sauce for numbles of beef: that is, he who has the charge of making the said sauce should take his numbles of well fattened beef and should wash them well and put them on fair and clean spits; and then should take his bread and cut it into round slices and roast it on the grill so that it is well roasted, and have there a fair and large cornue where he puts the said roasted bread; and should have a barrel of very good red wine and, if there is not enough in one, have two, and put in with the bread; and taste if the beef broth is good and sweet, and put in as much as is necessary of the part without fat in with the bread,and put in red wine vinegar so moderately that there is not too much, since if it is necessary he can add more; and then take powdered cinnamon, white ginger, grains of paradise, pepper, nutmeg, galingale, cloves, mace, and all other spices, and mix them with the said bread and strain very well; and check that you have fair and clean cauldrons or pots according to the quantity of the sauce which you have made in which to put it to boil. And the said numbles, when they have roasted as they ought, take them and cut them into proper little pieces, and then put them to boil in the said sauce; and being boiled all together, it should be put all in fair serving dishes, that is two pieces in each dish, with the said sauce on top.
Afterward, also, well-made pastry of fattened beef: and the pastry cooks will be well advised to take the numbles of well fattened beef and to tell those who cut up the beef to keep all the marrow of the beef to put with the numbles for eating.
And for the commoners let them take the thighs of the beef,and let them take such a great deal of them that they will serve everyone, and if the master pastry cooks are wise and well advised they will use moderately their salt with their spices so that it is not too salty.
Other versions of this recipe:
Lamprey Sauce (Du fait de cuisine)
Sauce pour lamprey (Two Fifteenth-Century Cookery-Books)