One hour roast beef sliced and in the fridge makes a great quick sandwich. Sure, sliced roast beef is an easy deli counter pick-up, but at about half the price per pound and about an hour of your time you can make it yourself with this pretty much foolproof method.
Instead of the pricier rib roast cut (an uncut rib-eye steak), you can make great roast beef with a lean rump or eye-of-round roast. These cuts offer a rich beefy flavor, but since they’re tougher they cannot endure overcooking. The key to tender success is a few minutes in a super hot (500 F) oven and a sharp temperature drop (300 F) for a nice rare to medium-rare finish. Take it out when your instant-read thermometer or barbecue temperature probe reaches 115 F to 120 F.
A meat thermometer or instant-read thermometer is absolutely necessary. Beef doneness is only about temperature. We say a one-hour rump roast, but your timing is dependent on how big your roast is and what shape it is. Geometry counts. A longer thinner roast will reach doneness in less time than a thick squatty roast. So your big one-hour rump roast could easily be a 1 1/2-hour rump roast. Don’t worry, just use a thermometer, because you can’t very well check it by cutting into it like you might a steak.
You can season any way you like, including using a paste made with seasonings and mustard, but we keep it simple with a blend of kosher salt and coarsely ground black pepper (more pepper than salt). For maximum tenderness — critical when served in a sandwich with no knife and fork to assist — slice the beef as thinly as possible with a sharp kitchen knife or, better yet, the electric knife buried in your dining room sideboard waiting for November turkey duty.
