Preheat the Oven - Adjust the oven rack to the center position and preheat to 275ºF (135ºC). Place a large 12-inch cast iron skillet in the oven to warm.
Season the Steaks - Line a sheet pan with foil and place a wire rack on top, set aside. Dry the steaks with a paper towel to remove excess surface moisture and transfer them to the wire rack. Generously season the meat with salt and ground black pepper on both sides.
Cook the Steaks - Place steaks in the oven and cook for about 15 to 25 minutes, depending on the thickness. Remove from the oven and set aside.
Sear the Steaks - Remove the cast iron pan from the oven and transfer it to the stovetop. Heat the pan over high heat and add the oil. Once the oil is hot and just beginning to smoke, carefully add the steaks to the pan.Sear the first side until a deep brown crust is formed, about 2 minutes. Flip and sear the other side for about 1 ½ to 2 minutes. Use tongs to turn the steaks on their sides to cook and render the remaining fat, about 2 minutes total. Add one tablespoon of the butter to the pan, melt and use a spoon to briefly baste the tops of the steaks.
Rest the Meat - Transfer the steaks to a clean plate and allow them to rest at room temperature for 10 minutes.
Red Wine Sauce - Reserve 1 tablespoon of the steak drippings in the cast iron pan and heat over medium. Once the drippings are warm, add the garlic and shallots. Saute and stir frequently, about 1 minute. Add red wine, balsamic vinegar, rosemary sprig, and thyme sprigs. Bring the mixture to a rapid simmer over high heat. Allow to reduce until thickened, about ¼ a cup, 3 to 5 minutes. Add in beef stock, and rapidly simmer over high heat until the sauce is reduced and thickened to about ½ cup, about 4 to 5 minutes. Remove rosemary and thyme, discard. Turn off the heat and whisk in 1 tablespoon of butter. Taste and season with more salt and pepper as desired.
To Serve - Garnish the steaks with chopped thyme, rosemary, and parsley before serving.
Notes
When in the Oven: I recommend checking the temperature using a meat thermometer at 15 minutes, then every 5 minutes until target doneness is reached, 90 to 95ºF (32 to 35ºC) for medium-rare, or 100 to 105ºF (38 to 41ºC) for medium.
When Searing: Aim for an internal temperature of 120 to 125ºF (49 to 52ºC) for medium-rare or 130 (54ºC) for medium.