Ball tip, round tip, crescent -- a sirloin tip roast goes by many names -- but whatever your local butcher calls it, this roast makes for a juicy and satisfying dinner. As this type of roast is only a cut away from the sirloin, it is a tender cut of beef well suited to dry roasting or to braising in a bag. By choosing a roaster bag, commonly referred to as an oven or roasting bag, a sirloin tip roast can be one of the easiest meals to prepare for your family. Instead of spending time watching over the roast during cooking or cleaning up a dirty pan, you can spend your attention elsewhere.
Preheat the oven to 350 degrees Fahrenheit. Place the open oven bag or roasting bag in the baking pan, and set aside.
Season the roast with your favorite herbs and spices. Rosemary or thyme pair especially well with beef, as do garlic, onion powder, as well as salt and pepper. Alternatively, you may use a seasoning packet from the spice aisle of your grocery store. Many seasoning packets are made especially for cooking roasts.
Place the seasoned roast in the open oven bag. Add the vegetables and water. The amount of liquid you need varies by the size of the roast. The goal is not to cover the roast, but to add only enough liquid to provide some moisture during cooking. This method of cooking braises the beef, which results in a tender, moist roast. A three-pound roast will require only a small amount of water.
Close the bag, using the nylon tie provided in the package of roasting bags. Cut three or four small slits near the tied part of the bag. This allows steam to escape during the cooking process.
Insert the meat thermometer through the closed bag, into the thickest part of the roast. Be sure the thermometer is not touching the sides or bottom of the pan, as that will affect the temperature readings. Using a meat thermometer is a quick way of ensuring the roast does not overcook.
Place the pan in the lower part of your oven, for approximately 1 ½ to 2 hours. Exact cooking times vary by the size of the roast and desired doneness. A sirloin tip roast retains its moisture and flavor best when cooked to medium-rare, or 145 degrees F.
Remove the pan when your roast has reached the desired temperature, and allow the roast to rest in the pan for five to 10 minutes. Carefully untie the oven bag, remove the roast and vegetables, and serve on a platter with your family’s favorite side dishes. Clean up is as easy as throwing away the bag, leaving you more time to enjoy dinner with your family.