- Preheat oven to Gas 4, 180ºC, 350ºF. Weigh joint and calculate cooking time: Rare - 20 minutes per 450g/½kg (1lb) plus 20 minutes Medium – 25 minutes per 450g/½kg (1lb) plus 25 minutes Well done – 30 minutes per 450g/½kg (1lb) plus 30 minutes
- Place joint in a shallow foil lined roasting tray. Add the joint; arrange onion quarters and frozen cranberries around the joint and spoon over the port and oil.
- Scrunch the foil around the bottom of the joint to catch juices close around the joint.
- Remove joint from oven and allow to stand for at least 10-15 minutes.
- Pour all the juices into a small pan and add the Port and cranberry sauce. Fast simmer and reduce to the desired thickness.
- Serve thick slices of beef with roasties,Yorkshire puddings and seasonal veg.