From the ArcaMax Publishing, The Culinary World, with Chef James Newsletter:
http://www.arcamax.com/news/chefjames/s-217494-216181
Taillevent, 'Le Viandier'
"Take a leg of mutton freshly cooked, and chop it as finely as
possible in a dish of onions. Stew these ingredients with a little
verjuice, butter, and ground white ginger mixed together and seasoned
with salt."
Courtesy of FoodReference.com.