have no idea what kind of monitoring they have in place.
What if they make screenshots of your desktop every X minutes?
If you are sure that monitoring is performed somewhere else, and no spyware installed on your computer, than any kind of SSL-connection would work. VPN, ssh-tunnel to some server outside your office network or even https:// to destiation website.
The only thing you should care about is SSL-certificate verification
because cert can be replaced on-the-fly with fake one issued by traffic monitoring tool. (mitmproxy, tcpcacther, SSLStrip, Fiddler2 and others do this trick).
What comes to Tor, I haven't heard about tools that can monitor Tor traffic. I'm not 100% sure this is impossible, but at least very nontrivial, since Tor makes 'onioned' SSL connections and only 'outer' layer is visible to your network admin. So I feel using Tor Bundle in your situation is pretty much safe.