Grill, broil or pan fry steaks to desired doneness; transfer to a platter and keep warm.
In a large skillet, melt butter over medium heat and sauté shallots and garlic. Add cornstarch, salt, mustard, and black pepper; combine thoroughly. Stir in Worcestershire sauce, lemon juice and vermouth.
Allow sauce to come to a simmer and thicken; place steaks back in skillet turning to coat both sides with sauce. Bring the sauce back to a simmer: cook for two minutes. Remove from heat and place steaks on a platter. Pour sauce over steaks. Garnish with chives.