Step 1

Position a rack in the middle of the oven and preheat to 375 degrees. Generously grease a large, rimmed baking sheet with butter.

Step 2

Scatter the onion slices and a generous amount of herbs on the baking sheet, then lay the chicken breast halves on top, skin side up, in a single layer. Sprinkle with lemon juice, then season lightly with salt and pepper. Roast for 30 to 40 minutes, until the meat’s juices run clear, and the internal temperature is 155 degrees. Do not overcook. Let the chicken rest for 5 minutes and check the temperature again, it should be Let cool.

Step 3

Discard the herbs and onions. Remove and discard the skin and bones and shred the chicken, or cut it into slivers or small cubes and transfer to a bowl. Add the tarragon and season lightly with salt and pepper, tossing to incorporate.

Step 4

In a separate bowl, stir together the sour cream and mayonnaise until combined. Add to the chicken a bit at a time to produce a salad that is creamy but not wet. Mix in more of the sour cream and mayonnaise, to reach desired texture.

Step 5

Stir in the celery and the pecans, if using. Taste, and season with more salt and/or pepper, if desired. Serve right away or refrigerate and serve chilled.