Ideally, you should move a roast to the refrigerator and let it thaw out gradually, over the course of a day or two. But if you don't have that much time, you can still enjoy your roast beef dinner without leaving the roast out at room temperature, which is dangerous and can lead to foodborne illness. The cold water defrosting method can safely get your roast ready to cook. It should take about two and one-half to three hours to defrost an average-sized roast that weighs 3 to 4 pounds.
Place the frozen roast into a resealable plastic bag that holds the entire piece of meat. You can leave the frozen meat in its original packaging or remove it. Press out the excess air and seal the bag tightly.
Fill a clean sink or a large pot with enough cold water to completely cover the bagged roast. Do not use hot water. Fully submerge the sealed bag with the frozen roast in the cold water.
Leave the roast in the cold water bath for 30 minutes. Remove the bagged roast and empty and refill the container with cold water. Re-submerge the frozen meat and leave it for another 30 minutes. Continue this process of continually refreshing the cold water until the roast is completely thawed.