Okay, yeah, that's crazy. It would be MUCH easier to start with a Minimal Debian in the first place. But, just for kicks:

• GREAT article
• script to do it (it's circa 2006, however)
• lower-level commands
  • use apt-get remove purge to remove config files also
  • remove a package, telling it to ignore dependency-checking
  • package:deborphan — remove packages that are no longer required
    • the packages
    • [debian-administration.org] article
    • [linuxjournal.com] article
  • package:debfoster — remove packages that are no longer required
    • debian package
    • Ubuntu package
    • articles: [1] [2] [3]
  • package:gtkorphan
  • apt-mark-sync — meta-meta-tool