Whisk buttermilk, mayonnaise, shallots, dill, lemon juice, and salt in a small bowl until well combined. Season with pepper. Cover, and refrigerate until cold, about 30 minutes.
Arrange bacon in a single layer in a large saute pan, and cook over medium heat, turning occasionally, until crisp, 8 to 10 minutes. Drain on paper towels. When cool, crumble bacon into bite-size pieces.
Arrange lettuce on a platter. Top with bacon, eggs, salmon, and avocado. Drizzle with 1/2 of the dressing. Season with pepper, and serve with remaining dressing on the side.
This salad is so yummy! It was so good everyone wanted more.
Instead of arranging the salad on a large platter I plated up the salads individually and then passed the dressing on the side.
I would add another head of lettuce when serving 8.