For beef lovers, there is nothing like a big, beautiful roast. Richly browned on the outside, rare and juicy on the inside, perfuming the air with its savory smells, a good roast trumps just about any other meal. Unfortunately, the next day things are different. It is difficult to reheat leftover roast without it becoming well done, a terrible thing to those who love theirs rare. Fortunately, there are a few techniques to minimize the effects of reheating.
Place a piece of leftover roast beef, no larger than 1 lb., on a sheet of heavy-duty aluminum foil. Spoon pan juices from the roast over the top, then seal up the edges of the sheet to make an airtight pocket. Reheat in your oven at the lowest temperature, until just warm. The beef should be no more than medium rare when sliced.
Slice the leftover beef thinly. Stack several slices to make a pile 3/4 inch thick, with a small amount of pan juice spooned in between the slices. Wrap tightly in foil, and place in your oven at the lowest possible setting until warmed through, about 25 to 30 minutes. The top and bottom slices will be cooked, but those in the middle should be no more than medium rare.
Slice the leftover beef thinly. Stack several slices to make a pile 3/4 inch thick. Turn on your vacuum sealer. Place the sliced meat in the first bag, with a spoonful of pan juices. Vacuum seal the bag. Heat water in a small saucepan until it reaches a temperature of 135 degrees Fahrenheit. Drop the sealed bag of beef into the water, and monitor the temperature closely. As long as it does not go above 135 degrees F, it is not possible for the beef to cook beyond rare. Remove from the water bath and use as desired.