The answer appears to be "nowhere" at the moment. I'm looking at flights to HKG as well - cheapest I can find ex-EU is from IST at £1921. MIL, AMS etc are all around £2,200+. Given I paid £1500 ex-LIN in March, not quite the deal it once was.
Best advice I can suggest is to play around with the ITA Matrix tool (see the sticky) and hope something comes up....
The other option is to stack the PRIDE discount code with shareholder discount if you have it - is bringing ex-LHR down to £2,770 for our dates.