Remove the steaks from the refrigerator 20 to 30 minutes before cooking and allow them to come to room temperature.
Pat the steaks dry with paper towels.
Season both sides of each steak evenly with kosher salt and black pepper.
Heat a cast iron skillet over medium-high heat until very hot.
Add the olive oil and swirl it around to coat the bottom of the pan.
Carefully place the steaks in the skillet.
Sear the steaks without moving them for 3 to 4 minutes, until a deep brown crust forms on the bottom.
Flip the steaks using tongs.
Add the butter to the pan.
Tilt the skillet slightly and spoon the melted butter over the tops of the steaks continuously for 3 to 4 minutes for medium-rare, or until your preferred doneness is reached.
Transfer the steaks to a plate and loosely cover them with foil to rest.
Reduce the heat to medium.
In the same skillet, add the sliced shiitake mushrooms.
Cook for 4 to 5 minutes, stirring occasionally, until the mushrooms are browned and tender.
Add the chopped shallot and cook for 1 minute.
Stir in the minced garlic and cook for 30 seconds, until fragrant.
Pour in the red wine to deglaze the pan, scraping up any browned bits from the bottom of the skillet.
Allow the wine to simmer for 2 to 3 minutes, until it reduces slightly.
Add the beef broth, thyme leaves, and Worcestershire sauce.
Simmer for another 3 to 5 minutes, until the sauce thickens slightly and turns glossy.
Return the steaks to the skillet briefly to warm through and coat them with the sauce, or place the steaks on a plate and spoon the mushroom sauce over the top.
Sprinkle fresh thyme over the steaks and spoon extra sauce around the plate before serving.
Notes
Tips and Tricks
Bring Steaks to Room Temperature. Cold steaks straight from the refrigerator cook unevenly. Letting them sit out for 20 to 30 minutes before cooking helps them sear and cook more evenly all the way through.Dry the Steaks Before Searing. Patting the steaks dry with paper towels removes surface moisture. This helps create a better crust when the steak hits the hot pan.Use a Very Hot Pan. The cast iron skillet needs to be very hot before the steaks go in. If the pan is not hot enough, the steaks will steam instead of sear and you will not get that brown crust.Do Not Move the Steaks. Once the steaks are in the pan, leave them alone. Moving them too soon prevents the crust from forming properly.Rest the Steaks. Letting the steaks rest under foil after cooking allows the juices to redistribute. Skipping this step can result in a drier steak.Scrape the Pan When Deglazing. When you pour the red wine into the skillet, use a spoon or spatula to scrape up all the browned bits from the bottom. Those bits add a lot of flavor to the sauce.Taste the Sauce Before Serving. Before plating, taste the sauce and adjust the salt and pepper if needed.
Storing
Allow the steaks and sauce to cool completely before storing. Place them in an airtight container and refrigerate for up to 3 days. Store the steaks and sauce together to help keep the meat moist.
Reheating
Reheat on Stovetop - Place the steak and sauce in a skillet over low heat. Warm slowly, turning the steak occasionally, until heated through. Adding a small splash of beef broth can help loosen the sauce if it has thickened in the refrigerator.