how long to roast topside for medium rare
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.