Heat oil in a 12-inch skillet over medium-high heat. Season steaks with salt and pepper, and add to skillet; cook, turning once, until browned on both sides and cooked to desired doneness, about five minutes for medium-rare. Transfer steaks to a plate, and set aside. Return skillet to high heat, and add stock; cook until reduced to ½ cup, about 10 minutes. Pour into a bowl, and set aside. Return skillet to heat, and add butter; add garlic and shallots, and cook, stirring, until soft for about two minutes. Add mushrooms, and cook, stirring, until they release any liquid and it evaporates and mushrooms begin to brown for two minutes. Stir in reserved stock, cream, mustard, worcestershire, and hot sauce and then return steaks to skillet; cook, turning in sauce, until warmed through and sauce is thickened for four minutes. Transfer steak to serving plates and stir parsley and chives into sauce; pour sauce over steaks to serve.