A rump roast is a deceptively priced cut of meat. For the price, you can usually get a few great meals mixed with some of your favorite veggies. For the best results when baking a rump roast in the oven, choose "prime" or "choice" grades of roast. Meat rated at lower grades can be just as good, but they will most likely come out tough if oven roasted.
Check that your roast will fit in your oven as configured. Remove the top baking rack if necessary to allow room for your roast. Preheat your oven to 350 F.
Put the roast in the center of a large backing pan. Slice vegetables. Carrots, potatoes and greens work well when roasted. Arrange the vegetables around the roast toward the outside of the pan.
Insert the meat thermometer into the thickest part of the roast and put the roast in the oven.
Cook rump roast for at least 1 hour and 40 minutes for "rare." Make sure that the internal temperature of the meat is at least 120 F before removing from the oven.
Continue to cook the rump roast for at least 2 hours for "medium." The thermometer should read 155 F. Continued cooking may cause the roast to become tough and dry or burn the vegetables.
Remove the rump roast from the oven and carve in slices. Serve with vegetables.
Cooking at lower temperatures may help retain internal juices and cook just as thoroughly. The cooking times listed will differ, however, so check the meat thermometer to know when the roast is done.