This is an excerpt from An Anonymous Andalusian Cookbook
(Andalusia, 13th c. - Charles Perry, trans.)
The original source can be found at
David Friedman's website
Flank of Lamb Roast in the Oven. Take a medium-sized pot and put in it some water and half a spoon of vinegar ... [one and a half lines blank in the manuscript]
Other versions of this recipe:
Roast Lamb (An Anonymous Andalusian Cookbook)
Roast mutton (Le Viandier de Taillevent)
Roast Mutton in a little salt or with verjuice and vinegar (Le Menagier de Paris)