Command
du -h <dir> 2>/dev/null | grep '[0-9\.]\+G'
Replace <dir> with your desired directory (for root use / )
Explanation
du -h
Shows the directory and the sizes of each in a human readable format.
2>/dev/null
Discards output of non directories (such as /proc/)
grep '[0-9\.]\+G'
Sorts out directories that is 1+ GBs and up.
That’s it
Keep this command in your favorite command lists, it will be needed at really random times.