Make the dressing: mash 2 oz of blue cheese into the mayonnaise with a fork until a rough paste forms. Stir in sour cream, buttermilk, lemon juice, Worcestershire, hot sauce, and grated garlic. Season with salt and pepper. Refrigerate for at least 15 minutes.
Cook the bacon until deeply crispy. Drain and crumble once cooled. Dice and soak the red onion in cold water for 10 minutes, then drain.
Cut the lettuce: remove outer leaves, trim the very tip of the stem but leave core intact. Cut straight through the head into 4 equal wedges.
Place each wedge cut-side up in a wide shallow bowl or on a platter. Spoon dressing generously over each, using the back of a spoon to push some dressing into the layers.
Top with cherry tomatoes, crumbled bacon, drained red onion, remaining blue cheese crumbles, and sliced chives. Finish with cracked black pepper and serve immediately.