Season the pork with salt and pepper, and place on the lower rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook for 1 hour, turning the joint over after 20 minutes, then again after another 20 minutes.
Meanwhile, crush the juniper berries using a mortar and pestle, or use a small bowl and the end of a rolling pin. Tip into a bowl and stir in the cranberry sauce and port. Season with a little salt and pepper.
Brush half the glaze over the pork once you have turned the pork twice and there is 20 minutes' cooking time remaining. Finish cooking. Transfer the pork to a board or warm serving plate and leave to rest for 20 minutes.
Add the remaining glaze and the stock to the juices left in the base of the halogen oven and cook for 5 minutes or until heated through. Check the seasoning and pour into a small jug. Serve the pork cut into slices, with the sauce for pouring over and accompanied by roast potatoes and seasonal green vegetables.