1 x 5cm/2inch piece fresh root ginger, peeled and finely chopped
30ml/2tbsp rapeseed or olive oil
Preheat the oven to Gas mark 4-5, 180-190°C, 350-375°F.
For the Thai marinade; in a small bowl mix all the ingredients together.
Place the joint on a chopping board, score the skin, season and brush the marinade all over the joint.
Cover and marinate in the refrigerator for up to 2 hours.
Put the joint on a metal rack in a large non-stick roasting tin and open roast for the preferred, calculated cooking time, basting occasionally with any beef juices. Cover with foil if browning too quickly.
Remove the joint from the tin, transfer to a warm plate, cover with foil and rest for at least 20 minutes.