how long to cook a 3 lb. roast beef
The method of cooking a roast in a roaster is called braising. A three pound roast would cook aproximately 2 to 2 1/2 hours at 325. The inside temperature should be 140 degrees for rare, 160 degrees for medium, and 170 degrees for well-done. Use meat theomometer for this.+++Use a meat thermometer that you leave in the roast the entire time it cooks...it should reach the middle..and not hit a bone. Cook 22 minutes per lb. at 300 degrees.ut the oven up to 400 (lid on roaster) for 20 - 30 minutes and sear, then put the temperature down to â¦ 350 and cook 15 minutes per pound.   If the 4 lb. beef roast is thawed then sear as above and cook for 20 minutes per pound.