DRESSING: In a mixing bowl, whisk together the mayonnaise, sour cream, buttermilk and seasoned salt, until combined. Season with salt and pepper to taste.
Gently fold in 1/4 cup blue cheese crumbles. Transfer to a storage container with an air tight lid and refrigerate until ready to use.
SALAD: Place 1 wedge of lettuce on each of 4 salad plates. Pour blue cheese dressing over each wedge. Sprinkle with tomatoes, green onions, crumbled blue cheese, and bacon. Season with freshly ground black pepper to taste.
Cook's Note: To core the lettuce - Hold the head of lettuce in two hands, position it so the core is facing down, slam it down on a hard flat surface, turn it over and remove the core.