Smoked-Salmon Cobb Salad

INGREDIENTS

• 3/4 cup buttermilk
• 1/2 cup mayonnaise
• 1/4 cup minced shallots (from 2 shallots)
• 3 tablespoons chopped fresh dill
• 1 tablespoon fresh lemon juice
• 1/2 teaspoon coarse salt
• Freshly ground pepper
• 8 ounces bacon (about 10 strips)
• 1 head Boston or bibb lettuce, leaves torn into 3-inch pieces
• 3 large hard-cooked eggs, quartered lengthwise and halved crosswise
• 3 ounces smoked salmon, flaked with a fork into bite-size pieces
• 1 avocado, pitted, peeled, and cut into 1/2-inch dice