Cook in a pre heated oven at 230°C/gas mark 8. Place your Topside in a roasting pan and brown in the oven for 20 minutes. Then remove the pan, add a little water to it, and turn the oven down to 150°C/gas mark 2. Return the joint to the oven and cook for 25 minutes for every 500g in weight. When the joint has cooked, remove it from the oven, wrap it in foil and leave it to rest for at least ten minutes before serving.