With a colorful history dating back almost 100 years, the French dip sandwich has long been a staple of U.S. restaurants. Today, at-home cooks can make this sandwich by filling a French bread roll with sliced beef and possibly cheese, and serving it with beef drippings. Roast beef takes a prominent role in the sandwich, so you will want to use a quality roast that is tender, flavorful and juicy. Ideal roasts for making French dip would be either rib roast or strip loin roast; for less expensive options, consider a rump roast or top round roast.
Cook the Roast
Remove the roast from the refrigerator and season the exterior of the roast liberally with salt, pepper and either cooking oil or melted butter. Allow the roast to come to room temperature for at least 1 hour.
Preheat the oven to 450 degrees Fahrenheit.
Place the roast in a roasting pan and place the pan in the oven. Cook the roast until it slightly browns on the exterior -- about 15 to 20 minutes. Then, reduce the oven heat to 325 F and continue roasting until the center interior reaches 5 to 10 degrees below your desired level of doneness -- the roast will continue to rise in temperature after it is removed from the oven and tented. You will want to remove the roast from the oven when it reaches 125 F for medium rare, 130 F for medium or 150 F for medium well. To test for doneness, use an instant-read meat thermometer. Cook times will vary based on the thickness of your roast. Generally, however, after lowering the temperature you'll want to begin checking for doneness 15 minutes per pound. For example, you'll check a 4-pound roast for doneness after 60 minutes.
Prepare the Meat and Au Jus for Sandwiches
Remove the roast from the oven and place on a cutting board -- preferably one that has an outer well to catch meat juices. Tent the board and roast with aluminum foil. Allow roast beef to rest for at least 15 minutes before slicing.
Strain the pan juices from the roasting pan into a sauce pan and skim off any visible fat.
Prepare the jus. If your roasting pan is stovetop safe, place the pan on the stovetop and turn the heat to high. Once the pan is heated, deglaze it with red wine, beef stock and strained pan juices. Reduce the heat to medium low and reduce the sauce, whisking occasionally, for about 15 to 20 minutes until slightly thickened -- the finished au jus should still, however, be thinner than a typical sauce. Season with salt and pepper to taste.
If you do not have a stovetop safe roasting pan, add a small amount of beef stock to the still warm pan from the oven. Using a spatula to scrape up all the browned bits from the bottom of the pan that you can, then pour the stock and loosened bits into the sauce pan with your pan juices. Add the red wine and remaining stock to the sauce pan and simmer, whisking frequently, for 15 to 20 minutes until slightly thickened.
Thinly slice the roast beef and serve with au jus on French sandwich rolls.