How to find a high quality PhD advisor in another country?
It depends on your credentials and references. But having good record enables you to apply to many good schools (e.g., Princeton, MIT etc.) in the US/Europe, via dedicated online application sites. So you do not need to personally contact anyone. 

The other option is to use Findaphd.com, and other dedicated mailing lists who solicit PhD applications.

Of course, sending emails to professors, without knowing in advance whether they have the money to support a PhD student, is possible but has quite a low chance of success.  

You might also use your existing professional connections within your local academia to seek potential PhD opportunities.