- Preheat oven to Gas 4, 180ºC, 350ºF.
- Take joint and place in a large roasting pan. Season and drizzle with sesame oil. Place in oven and cook for ¾ of the calculated 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
- Mix together the Chinese sauce ingredients.
- 50 minutes before the end of cooking time add the vegetables (except pak choi - add this 10 minutes before the end of cooking) to the base of the roasting pan and spread into a single layer.
- Baste the joint and vegetables in the sauce. Return to oven and baste again after 10 minutes.
- When cooked allow meat to rest for 10 minutes before serving. Serve carved into thin slices with vegetables and drizzle with cooking juices.
- Also delicious cold - if there's any leftover in wraps or salad.