Reduce the beef stock on low heat in half.
Sautee the mushrooms in butter with chopped shallots and herbs de provence. Season with salt and pepper. Keep warm.
Season the filet mignon with salt and pepper and then brown the filets in butter.
Sear the foie gras dices on high heat. Put aside.
In each plate, arrange some of the mixed mushrooms. Set the filet on top. Sprinkle with the foie gras dices. Coat with the beef stock that has been reduced by half. Garnish with Chervil.