Chicken waldorf salad cups

Ingredients

• 1/2 cup whole-egg mayonnaise
• 1 tablespoon lemon juice
• 1 tablespoon water
• 1/2 barbecue chicken
• 1 large pink lady apple
• 2 stalks celery, trimmed and sliced
• 1/3 cup walnuts, roughly chopped
• 1 1/2 tablespoon chopped chives
• salt and pepper, to taste
• 4 iceberg lettuce leaves, trimmed into cup shapes
• chives and chopped walnuts, to garnish