Combine sour cream, salt, mustard, ... cup buttermilk and mayonnaise; mix well. Add crumbled bleu cheese and remaining buttermilk. Let stand 24 hours before using.
Place first 6 ingredients in ... low speed. Add mayonnaise and blend 1/2 minute at ... medium speed. Crumble bleu cheese by hand in very ... approximately 2 1/2 cups.