Sardines, Piedmontese

Scrape some sardines and place them in the oven to heat. Put in a saucepan
four well beaten yolks of eggs, one teaspoonful each of tarragon vinegar, malt vinegar
and made mustard, a small quantity of salt, and one-half tablespoonful of butter.
Stir the sauce over the fire until it is quite thick, but do not allow it to boil. Cut
some slices of bread, remove the crusts, and fry them in boiling lard or butter until
lightly browned. Drain the pieces of bread, arrange them on a hot dish, pile the
sardines on them, pour the sauce over and serve.