This isn't a slaw recipe but the dressing may be similar since it uses onions pureed with vinegar & blue cheese. If it sounds sort of like it you could experiment if nobody else comes along with the exact recipe you're looking for.

Here is a link that might be useful: Jackson Salad

I had a wonderful salad dressing a few years back at a friend's house. I asked for the recipe, read it but didn't write it down, it was simple, I would remember!
Guess what? I forgot! And she has moved across the country.
It was a small onion and a lot of sugar with rice vinegar pureed with Wesson Oil ..( I know!! So much better with olive oil!) and celery seed added after the stuff was pureed.
I don't know if you are meaning trhat the blue cheese was pureed with the dressing or just crumbled on the salad....but I suspect you could make a very good dressing with 1/3 cup rice vinegar, 1/2 a small yellow onion, 2 T sugar and 2/3 cup EVOO and 2 oz blue cheese, blended until thick and creamy.
Linda C