Avocado forms the base of creamy green goddess dressing in this everyday chicken salad recipe. Made with lots of green herbs, capers and scallions, it's tangy, vinegary and luxuriously creamy without the addition of any dairy or mayonnaise. Feel free to substitute other tender herbs you have on hand -- chervil, chives and tarragon would all nod to classic green goddess dressing. For the chicken, you can roast bone-in, skin-on breasts, use leftov…