You are looking for the cheapest solution to Hong Kong then have a look on this deal based on Air China (Star Alliance) when flying from Switzerland (Geneva). Return flights with a layover in Beijing are available already for €274. (Incl. all taxes, inflight meals and checked bag). Limited availability in spring 2018 so hurry up with booking if this is a deal you have been waiting for..
You can book your hotel room in Hong Kong through Booking.com or Hotels.com. Air China sale is available till 31st of March. Travel dates 30th of April to 11th of June 2018. Based on latest date of your outbound flight from Europe. Max stay 3 months.
Booking sample of cheap return flights from Switzerland to Hong Kong from €274!! You would fly from Switzerland to Hong Kong on Sunday, 21st of January. Your return flight from Asia to Europe woudl be then on 29th of January 2018.