Traditionally, Chateaubriand is served rare, in fact very rare. These days it isn't as common to serve a cut of beef this rare, so Chateaubriand is the perfect dish for a cooking method known as the reverse sear. The reverse sear starts by grilling meat at a low temperature to warm it through the middle and lightly brown the meat on the inside. Then it is moved to a high temperature to sear or more accurately caramelize the exterior. This method allows the lean and tender meat to be cooked to a desired doneness without drying it out.
Start with a large, 1 to 2 pound beef tenderloin roast of at least 1 1/4-inch thickness. Brush both sides with oil and lightly season with salt and pepper. If using a gas grill turn one side to the highest possible setting and the other to a medium low heat. For a charcoal grill, light enough charcoal to cover half the grill, leaving the other side empty. Place the beef tenderloin on the low temperature side and close the lid. For medium rare leave the tenderloin to cook for 5 minutes. For medium and above, leave it for about 7 minutes before opening the lid and turning the meat, leaving it in the low temperature zone. After an additional 5 to 7 minutes it is time to place it on the direct and high heat.
At this point the tenderloin should be browned on both sides and through the edges with little or not grill marks. Leave the meat on the high temperature with the lid closed for 2 to three minutes depending on the heat of your grill, then check. Now there should be dark grill marks and a rich and dark brown color to the cooked side. If not, continued grilling until these are evident. Once you have this appearance, turn the meat over and continued on the other side.
Once finished on the grill, move the meat to a cutting board, cover and leave to rest for 5 to 10 minutes. To top a traditional Chateaubriand, melt 2 tablespoons of butter with 2 tablespoons of olive oil in a heavy and hot skillet. Add one large, finely chopped shallot with 1/2 cup of white wine, 1/2 cup demi-glace, and 1 tablespoon fresh tarragon (2 teaspoons dried). Whisk together and heat until it thickens into a light gravy.
When the meat has rested, cut into thin strips against the grain and serve with the sauce. This dish is traditional side dish is chateau potatoes. These small potatoes are roasted in a heavy pan, covered in butter. Not a recipe for the dieter, but well worth the extra calories.
Of course the beef tenderloin steak is one of the more expensive cuts, but if you want to make a meal that is sure to impress, this is a good one to choose. Remember that I said that Chateaubriand is a recipe and not a cut of meat. This recipe has been adapted by a great number of cooks to use almost anything from fish to artichokes.