Roast beef is a traditional Christmas meal. While many people prepare a rib roast, a topside joint, also known as a round roast, can provide a leaner and less expensive alternative while still allowing your family to have roast beef at Christmas. Because it is such a lean cut of meat, however, a topside joint requires a bit of care to make sure the roast is moist and tender. For best results, ask the butcher for the corner cut of the topside joint. Make sure he knows you'll be oven roasting it and that you'd like it rolled and tied with a layer of fat on top.
Preheat the oven to 245 degrees Celsius (475 degrees Fahrenheit). While the oven is preheating, allow the meat to rest at room temperature.
Place the chopped onion in the centre of the roasting pan. The onion serves as a rack to keep the meat from sticking to the pan and also will add flavour to the pan juices.
Season the meat with salt and pepper to taste and rub the olive oil over the roast, making sure to coat the ends well. Place the beef on top of the chopped onion. Surround the roast with vegetables tossed in olive oil if desired.
Place the roasting pan in the oven and turn the temperature down to 205 degrees Celsius (400 degrees Fahrenheit). Baste the roast with the pan drippings at 15 minute intervals.
Check the temperature after 45 minutes. The meat should be at 57 degrees C (135 degrees F) for medium rare and 65 degrees C (150 degrees F) for medium. If it is not done, continue to check the temperature at 5 minute intervals. Do not roast a topside joint to more than medium, as it will dry out.
Take the roast out at the appropriate temperature, put it on a platter and tent it with foil. Allow it to sit for 30 minutes while you prepare gravy and finish your side dishes. Do not skip the resting time; this is actually the final step in the cooking process where the meat finishes cooking and the juices are redistributed throughout the roast. The meat will be more tender and easier to slice at the end of the resting time.