Saute onion, carrot an celery in 1 tablespoon butter until lightly browned.
2
Add Madeira and reduce to a glaze. Add the veal stock and reduce by one-half. Season to taste with salt & pepper. Strain through a fine-mesh strainer or cheese cloth.
3
Flame the truffle in the cognac. Add the truffle and foie gras to the sauce. Just before serving, add 1/4 cup butter for extra flavor and shine.