The most expensive beef cut, filet mignon, comes from the beef tenderloin, the most tender part of beef. The steaks are cut about 2 1/2-inches thick, and when they're cooked to medium-rare, they are tender enough to cut with a butter knife. The cut from the center, thickest part of the tenderloin is commonly used to prepare chateaubriand, a recipe developed by Montmireil, personal chef to Vicomte Chateaubriand.
Due to low fat marbling, filet mignon does not have as much beefy flavor as other steaks and benefits from seasoning. Sprinkle the steaks with salt and pepper, using other spices such as garlic or onion powder, if desired. To compensate for the lack of fat, many chefs wrap filets with thick-sliced bacon held in place with a toothpick. Set out the filets for about 30 minutes before cooking to bring them up to room temperature. When preparing beef tenderloin entirely under an oven broiler, add a few tablespoons of cooking oil or lard to an oven-proof skillet and pre-heat the pan under the broiler. Filets can also be prepared in a shallow broiler pan, but this does not allow the opportunity for deglazing and making a pan sauce on the stovetop.
A light sear on both sides of a filet boosts the flavor of filet mignon, but it's not required. For this option, sear the filets for about 3 minutes per side on the stovetop. Transfer the skillet to the broiler for about 5 minutes for medium-rare, or up to 10 minutes for well-done steak. The oven rack should be positioned 4 to 6 inches from the broiler heating element. Alternatively, place the raw filets in a preheated skillet or broiler pan. Broil for about 9 minutes per side for medium-rare or 12 minutes per side for well-done. Use a meat thermometer for the most accurate determination of doneness; cook to 135 degrees Fahrenheit for medium-rare and up to 155 F for well-done filets. Allow the filets to rest for about 3 minutes before slicing so the juices redistribute throughout the meat instead of pooling on the plate.
The thick center cut for chateaubriand must be pounded flat to promote even cooking. Stand the steak on end and pound it with a meat mallet, flipping occasionally, to a thickness of about 1 1/2 inches. A heavy cast-iron skillet also works well for flattening chateaubriand filets. Follow the same light seasoning as for filet mignon, but brush the steak generously with melted butter or olive oil. While the cooking process is the same as for filet mignon, the thinner meat cut results in a shorter cook time. Check the internal temperature with a meat thermometer to cook to rare or medium-rare. After the resting period, slice the meat thinly at a slight angle before serving.
Pan searing leaves behind tiny morsels of stuck-on meat that are packed with flavor. Use the pan drippings and stuck-on bits to make a flavorful sauce to complement the filets. Splash a bit of wine and beef broth in the pan and scrape the bits off the sides of the pan. The liquid takes on a deep brown color as the pan deglazes. Season the deglazing liquid with herbs and spices and simmer to reduce by half. A splash of whipping cream thickens the liquid into a rich, gravy-like sauce. Chateaubriand is always served with a pan sauce. The complicated process requires reducing 1/2 cup of white wine -- with shallots, wine, and mushrooms -- to almost nothing, then mixing in 1 cup of beef broth and reducing by half. Strain the sauce and stir in a compound butter mixture of butter, lemon juice, parsley, salt and pepper to thicken and enrich the sauce.