Patience is a virtue. Sub zero for 12-24 hours is the way to go.

Plain old evap also works quite well. A slower evap results in bigger and purer crystals.

I prefer to use a wide shallow dish for ease of scraping up.

MHRB isn't really that different from ACRB, in terms of yields.

You could give it a shot, but it's likely that your soup is already spent and will pull nothing.