How to Make It
In a small skillet, melt butter over medium-low heat. Add pecans. Cook stirring constantly for 6 to 8 minutes or until fragrant and toasted.
Whisk together mayonnaise, tarragon, lemon juice, and lemon zest in a large bowl. Stir in chicken, apples celery, and onion until blended. Add salt and freshly ground pepper to taste.
Cover and chill 2 to 24 hours. Stir in 1/2 cup toasted pecans just before serving. Sprinkle with remaining pecans.