The ="" there is unnecessary; writing an attribute name only implies an empty value.

If you’re going for shortest valid document at all, <!doctype html> is enough, provided the document exists in a context that makes title optional (e.g. email or <iframe srcdoc>) and that the charset is declared out-of-band.

You may be able to use a UTF BOM instead of the meta tag, or I think someone mentioned elsewhere having the server declare the character encoding in a header. I guess it depends on whether you count the header size which is better for golfing.