Egg White and Avocado Salad

INGREDIENTS

• 6 hard-boiled eggs, whites only, chopped into 1/2-inch pieces
• 1 rib celery, cut into 1/4-inch pieces
• 1 avocado, cut into 1/2-inch pieces
• 1 Granny Smith apple, cut into 1/4-inch pieces
• 2 tablespoons light mayonnaise
• 1 tablespoon finely chopped fresh flat-leaf parsley
• 2 teaspoons freshly squeezed lemon juice
• Pinch of cayenne pepper
• 1/2 teaspoon coarse salt
• 1/4 teaspoon freshly ground pepper
• Butter lettuce, for serving