ROMAINE AND BROCCOLI SALAD

Ingredients

• 2 whole heads of garlic, unpeeled
• Olive oil
• 1 cup mayonnaise
• 1/2 cup buttermilk
• 2 1/2 tablespoons minced fresh chives
• 1 tablespoon fresh lemon juice
• 1 1/4 teaspoons celery salt
• 1/4 teaspoon (scant) freshly ground black pepper
• 1 18-ounce package hearts of romaine (about 3), coarsely torn
• 1 1-pint container grape tomatoes
• 1 1/2 cups small broccoli florets
• 1 small English hothouse cucumber, thinly sliced
• 1 8-ounce package thinly sliced mushrooms
• 1 small red onion, sliced paper-thin