Preheat oven to 400 degrees. Allow steaks to come to room temp, about 20 minutes.
In a large skillet, melt 2 tablespoons butter over high heat. Salt and pepper the steaks. Sear steaks 1 to 2 minutes on each side working with one or two at a time. Place seared steaks on a cookie sheet. Set aside (not in the oven.) One very important note, be very careful not to sear the steaks to long. They need to be seared quickly on a very hot pan then removed.
Melt 2 Tablespoons butter in the pan your steaks were seared in, over medium heat. Add onion and garlic, cook, stirring often 5 minutes or until onion is soft. Add chicken broth and wine, stir and scrape the bits off the bottom on the pan. Cook 7 to 9 minutes or until liquid is reduced by two-thirds. Stir in vinegar and Worcestershire. Add remaining butter and stir until melted and mixture is smooth. Stir in parsley.
Place steaks in the oven and cook any additional time needed to the desired degree of doneness being careful not to overcook. Serve immediately with sauce.