Cooking a sirloin roast to perfection does not have to be difficult. With a simple meat thermometer, you can serve a mouth-watering sirloin roast done just the way your family likes. Knowing the approximate cooking times saves you the hassle of constantly checking the roast in the oven, or on the grill. Once you have the sirloin roast seasoned and in the pan, you're ready to cook.
Before you cook
If you're cooking a roast in an oven, preheat the oven to 148 degrees C (300 degrees F). If you plan to cook on the grill, get your charcoal to the grey state before cooking. Allow the roast to come to room temperature before seasoning and cooking.
For a rare sirloin roast
Sear the roast on all sides on the hob in a frying pan if you plan to cook the roast in the oven. This will help lock the juices in the meat. Place the roast in your roasting pan on a shallow cooking rack. Cook in the oven for approximately 16 to 20 minutes per pound. On the grill, allow the roast to cook for approximately 30 minutes per kg (2 lb), turning the meat once or twice during cooking over indirect heat before checking temperature. The internal temperature, for both methods, should be 48.8 to 51.6 degrees C (120 to 125 degrees F). Let the roast sit, tented with foil for 15 to 20 minutes before carving.
For a medium roast
Figure on approximately 46 to 50 minutes per kg (2 lb) for a roast in the oven in a roasting pan. For grilling, allow 20 minutes per pound, turning the roast several times during the cooking process. The roast is at medium doneness when the internal temperature reaches 62.7 to 65.5 degrees C (145 to 150 degrees F) at its thickest point. Allow the roast to rest, covered, for 15 to 20 minutes before serving.
For a well-done roast
Cook a sirloin roast well done by letting the internal temperature reach 68.3 to 71.1 degrees C (155 to 160 degrees F). This will take a roast approximately 1 hour 20 minutes to 1 hour 30 minutes per kg (2 lb). Start taking the temperature of the meat after five hours of cooking time. If cooking on the grill, make sure to keep the roast over indirect heat the entire cooking time.
Use a thermometer
A meat thermometer, whether it be a simple dial probe type, or a digital model that remains in the meat for the entire cooking process, is essential to cooking roasts and steaks to perfection. While cooking times can be a good rule of thumb to follow, differences in oven temperatures, grills and even the type of pans used, can alter the basic cooking times.