Antonie van Leeuwenhoek: Antonie van Leeuwenhoek, Dutch microscopist who was the first to observe bacteria and protozoa. His researches on lower animals refuted the doctrine of spontaneous
1 Rub the dripping or butter over the joint. 2  Season generously with salt and pepper. 3  Roast the beef topside according to your desired temperature: 20 minutes per 500g, plus an additional 20 minutes for rare; 25 minutes per 500g, plus 25 minutes for medium; 30 minutes per 500g, plus 30 minutes for well done. Roast the beef topside according to your desired temperature: 20 minutes per 500g, plus an additional 20 minutes for rare; 25 minutes per 500g, plus 25 minutes for medium; 30 minutes per 500g, plus 30 minutes for well done.
Continue to cook the sirloin roast until a meat thermometer registers 130 degrees at the CENTER of the roast for medium rare at the center, medium on the ends. This should take around 20 â 30 minutes per pound, but never rely on exact times. Use a meat thermometer instead.