In a medium mixing bowl, whisk together mayonnaise, buttermilk, and all seasoning ingredients until smooth and creamy. Cover and refrigerate for at least 2 hours.

Fine-dice the red onion, place in a small bowl, cover with water, add champagne vinegar, and soak for 30 minutes. Drain and set aside.

Cut iceberg lettuce into 4 to 6 wedges and rinse under cold water. Pat dry.

In a skillet, melt salted butter, add breadcrumbs and sauté until golden brown, about 5–7 minutes. Mix in lemon zest, let cool.

On a large platter, arrange lettuce wedges. Drizzle dressing over each wedge, layer with bacon, eggs, tomatoes, and soaked onions.

Sprinkle breadcrumbs over the wedges and garnish with chives. Serve immediately.