Command not found handler for non-searched commands?

["Benjamin R. Haskell" <zsh@benizi.com>]

I use autocd quite a bit.  And often the first thing I want to do when 
starting a new project is to create a directory and cd into it.  I tried 
creating the following command_not_found_handler:

command_not_found_handler () {
   local dir create
   echo HEREIAM >&2
   (( $# == 1 )) || return 1
   [[ $1 == */* ]] || return 1
   dir=$1
   read -q "create?Create $dir [y/N]? " || return 1
   mkdir -p $dir || return 1
   cd $dir
}

But, it doesn't get called when I need it:

## when I don't need it:
$ fake-command-here
HEREIAM
zsh: command not found: fake-command-here

## when I do need it:
$ ~/tmp/one-off-project
zsh: no such file or directory: /home/bhaskell/tmp/one-off-project

I see from the description of how commands are found that it won't get 
called when there's a slash in the command.  Is there a way to force it? 
Otherwise, is there another, easy way to accomplish my goal?

-- 
Best,
Ben