Remove the stem of the head of iceberg lettuce. Slice the head of lettuce into quarters (or equal wedges) and wash it thoroughly. Place the lettuce wedges on a large plate that is covered with paper towels or on a wire rack to dry.
Once the lettuce is dry, remove the paper towels from the plate. Sprinkle the chopped tomatoes, onions, bacon crumbles, and blue cheese crumbles on top of the lettuce wedges.
Combine all of the dressing ingredients (Greek yogurt, half and half, and ranch seasoning) into a small bowl and mix until smooth.
Drizzle the ranch dressing over the top of the salad, adding as much or as little as you like, and then enjoy!
Notes
Washing the lettuce: Be sure to wash it thoroughly with cold water, but also give it enough time to dry. I like leaving them face down on a paper towel-lined plate or a wire rack to absorb the water.
Dressing: Don't dress the salad until you are ready to eat, iceberg lettuce does wilt quickly with dressing.