Preparation

• Combine the wine, Sauternes, onion, mushrooms, garlic, parsley, pepper, and rosemary in a medium saucepan. Bring to
  a boil, lower the heat, and simmer briskly to reduce the liquid by half, about 10 minutes. Add the broth and simmer to reduce by half again, about 13 minutes. Strain the liquid and discard the solids. Clean the saucepan and return the strained liquid to the pan. Reduce until there is just more than 1/3 cup liquid remaining, about 5 minutes.
• Position a rack in the center of the oven and heat to 425°F. Heat a large cast-iron skillet over high heat. Pat the beef dry with paper towels. Season both sides generously with salt and pepper. Sear, in batches if necessary, for 2 minutes per side. Transfer the beef to a baking pan and roast until medium rare (130°F), about 8 minutes. Tent with foil and let rest.
• 减少返回酒炖。除掉the heat and whisk in the butter. Season to taste with salt. Serve the sauce with the steaks.