Combine the following ingredients (in a tall & deep container, preferably, in which you wish to store the dressing, if using an immersion blender):
1 & 1/2 Tbs. white wine vinegar
1 Tbs. prepared horseradish
3 or 4 pressed cloves of garlic (or more, to taste)
1 Tbs. milk & 1 tsp. lemon juice (to replace 2 Tbs. buttermilk in case you don't have it sitting around)
1 Tbs. grated onion (I use fairly fine holes on a grater)
1/4 tsp. onion salt
1/4 tsp. garlic salt
1 tsp. freshly ground black pepper
1/4 tsp. freshly ground white pepper
1/2 tsp. dry mustard
Blend the above till well mixed, using an immersion blender, food processor or a standard blender.
Add to the above:
1/2 cup sour cream
1 cup mayonnaise (Hellmans!)
4 Oz. blue cheese (I currently use Boar's head crumbled), to be processed into the dressing
Blend the above until smooth then stir in another 4 oz. of crumbled blue cheese. Keeps a long time, but will probably get bluer - Hey, it's alive!