In the bowl of a food processor, add blue cheese, buttermilk, sour cream, scallions, and lemon juice. Pulse until the scallions are finely chopped.
Pour the dressing into a bowl and mix in the mayonnaise by hand. Season to taste with salt and pepper. If you prefer a chunky blue cheese dressing, add more crumbles.
Blue cheese: You’ll need some for the salad dressing and more to scatter on top. If you don’t care of blue cheese, substitute ranch dressing and shredded cheddar cheese.
Buttermilk: Adds beautiful acidity to the dressing. You can make your own by pour 1 cup full-fat milk into a bowl. Stir in 1-2 tablespoons lemon juice or white vinegar and let sit for 10 minutes to curdle and thicken.
Yield: One batch of the recipe makes almost 2 cups of luscious dressing.
Storage: Stored in the fridge, the dressing should last at least 5 to 7 days after you make it. This recipe has some lemon juice (instead of chemical preservatives found in store-bought dressings) so it can stay fresh for a while.
Use the food processor: It's tempting to just mix everything up in a bowl to save on clean-up, but I find the blade of the processor minces the scallions into the dressing better than I ever could.
Serving suggestions: Enjoy with raw or roasted vegetables as a dip, or make a spinach salad with roasted beets. A spoonful on a grilled burger is pretty fabulous, too. Or serve it with sliced onions and summer tomatoes as an impromptu salad.