Tuna Salad with Grapes and Lemon Tarragon Dressing

Name: Tuna Salad with Grapes and Lemon Tarragon Dressing
Ingredients: 1/2 cup mayonnaise; 1½ teaspoons finely grated lemon zest; 1½ teaspoons lemon juice; 1½ teaspoons tarragon vinegar; 1/2 teaspoon dried tarragon leaves, crushed; 1/8 teaspoon ground black pepper; 2 cans (6 oz. each) solid white tuna (drained); 1 cup red California seedless grapes, halved; 1/3 cup toasted walnuts, chopped; 1/3 diced celery; 2½ tablespoons diced yellow onion; 1 each hard boiled egg, peeled and chopped (optional); 1/3 cup Lemon Tarragon Dressing (see below)