Taiwan visa applications in the US require supporting documents from outside Taiwan to be authenticated by the government of Taiwan. TECO informed me of two ways to do this:
Have it authenticated at the Taiwanese consular office for the jurisdiction where is was issued.
If the document is from outside the US, and that option is not available, have it authenticated by the US embassy for the jurisdiction where it was issued, and then have the authentication certificate authenticated by TECRO in Washington, D.C. (It is unclear what type of authentication the US embassy would provide in this case).
In my case, I have a document from Mongolia that I need to authenticate, but TECO in Mongolia does not offer authentication services, and the US embassy there may be unable to authenticate a document for me when I am not there in person. I haven't been able to contact the US embassy due to COVID-related suspensions, and I cannot enter Mongolia due to border closure.
Are there other pathways to getting the document authenticated for TECO?