1. In a small bowl, combine the butter, garlic & herb sauce mix, poultry seasoning and crushed garlic. Use a fork to stir together until well mixed. Cover and refrigerate for 15 minutes or until butter mixture is firm but not hard.
2. Heat oven to 450 degrees F. In bottom of roasting pan, place celery and carrot sticks and half of the diced onion. Add chicken broth; set aside.
3. Rinse thawed turkey under cold water and pat dry with paper towels. Using your fingers, carefully loosen the skin around entire bird. Chop the butter mixture into small pieces. Place half of the butter pieces under the skin of the turkey. Rub remaining butter pieces on the outside of the skin. Season inside and outside of the turkey with salt and pepper. Stuff turkey cavity with remaining onions, fresh herbs and lemon slices. (Truss if desired.) Insert a pop-up thermometer at an angle (about 3 inches down from the neck cavity and 2 inches from the breast bone).
4. Place the turkey, breast-side up, on a rack over the vegetables in a roasting pan. Place in a preheated oven and reduce temperature to 325 degrees F.
5. Roast at 325 degrees F for 1 hour. Then, basting with pan juices every 20 minutes, continue roasting about 2-1/2 hours more or, if turkey comes with a thermometer, until it pops up.