Blue cheese salad dressing can be very simple. If you start with good blue cheese, you just need the creamy base for it. Well, even if you use non-great blue cheese, all you need is the creamy base. But you don't need to add herbs, spices, or other flavors. Let the blue cheese do all the work.
To make it even better, crumble some blue cheese on top of the salad as well. I'd suggest using your favorite blue cheese - or at least one that you like to eat. It's what you're going to taste. This is also a great way to use up bits and pieces of blue cheese that you have hanging around in the refrigerator.
Blue Cheese Salad Dressing
This is more of a formula than a recipe with measurements, but this lets you make exactly as much as you need.
Stir the mayonnaise to loosen it up a bit. Combine equal parts of mayonnaise and buttermilk. Stir or whisk to combine and smooth it out.
Use a fork to make crumbles from the cheese. Add an equal amount of cheese as you have mayonnaise. Stir to combine, breaking up any large chunks, but leaving the smaller bits - you want it to have texture.
Serve on top of your favorite salad greens. Refrigerate any leftover dressing.