The real Unicode minus sign?
Only if you activate the Unicode Hex Input in the System Preferences. The you can access the minus sign by pressing Option 2212.

P.S. If you have a lot of special characters to type and you don't want to use PopChar or the character palette you may try tools like Typinator: http://www.ergonis.com/products/typinator/
With such tools you can define your own Unicode text replacements, like every time you type "#-" it woud become am real minus sign, "#tm" would become ™ and so on. Even faster than PopChar.

Thank you Ralf, the real unicode minus was the one I was looking for yes.
That's a handy tool!

Artur