Lobster Vol-au-Vent

Rub together four tablespoonfuls of butter and one and one-half tablespoonfuls
of flour. Pour on this by degrees one pint of boiling white stock, boil up, and add
the juice of half a lemon, a little salt, a few grains of cayenne, the yolks of two eggs
beaten in a little cold water, and the meat of two small lobsters cut into dice. Stir
over the fire for one minute, fill a vol-au-vent case, place the cover on and serve.