In a skillet over medium-high heat, fry the steaks in half the butter and all the oil until done to your liking. Season with salt and pepper. Transfer to a plate and keep warm.
In a saucepan, bring the broth, wine, bay leaves and pepper to a boil. Reduce by 3/4.
Meanwhile, in the same skillet over medium heat, soften the shallots in the remaining butter. Deglaze with the vinegar and reduce until almost dry. Dust with the flour. Cook, stirring constantly, for 1 minute. Add the wine reduction and the mustard. Simmer until syrupy. Add any juice released by the meat.
Spoon the sauce over the steaks. Serve with Jerusalem Artichoke Gratin (see recipe, right).