The cooking time for a sirloin beef roast, also known as a spoon roast, varies according to size and preference, but generally requires between one and three hours. When cooking a slow roast in a crock pot or slow roaster, it requires 6 to 8 hours of cooking.
The cooking time varies based on how well-done the diners like the meat. A spoon roast is cooked slowly to make it tender. Unlike other types of roasts or steaks, it requires a longer cooking time to achieve the desired texture and internal temperature of the meat. The slow roast should rest for approximately 15 minutes after cooking, according to RachaelRay.com. The meat should be carved against the grain.