This is an excerpt from Le Viandier de Taillevent
(France, ca. 1380 - James Prescott, trans.)
The original source can be found at
James Prescott's website
Black Pepper [Sauce]. Crush ginger, burnt bread and pepper, steep in vinegar and verjuice, and boil. (BN manuscript, p. 34.)
Other versions of this recipe:
BLACK PEPPER (Le Menagier de Paris)
Pepper sauce that is genuine (Libro di cucina / Libro per cuoco)
To make a pepper sauce (Wel ende edelike spijse)