In a bowl, mix together mayonnaise, sour cream, and buttermilk until smooth and well-combined.
Stir in garlic powder, onion powder, salt, and pepper to taste.
Crumble the blue cheese into the mixture, leaving some larger chunks for texture.
Stir in lemon juice to balance the richness of the dressing with a touch of acidity.
Cover the dressing and refrigerate for at least 30 minutes to allow the flavors to meld.
Give it a final stir before serving as a dressing for salads, or as a dip for vegetables and wings.
