Brining is a great way to produce a turkey with moist breast meat and good flavor, but it also tends to make the meat a bit spongy–a texture that's still preferable to dried-out meat, but not quite perfect. Dry curing (also called “dry brining”), in which you put salt and spices directly on the skin of the bird and let it chill for a few days, has all the advantages of brining without the mess or the texture problem. (See p. 55 for details and how-to photos.) Like brining, this technique requires some advance planning: about three days in the refrigerator. But it's well worth the trouble.
Note: The amount of salt you use depends on the size of your turkey. Use 2-½ tablespoons if your bird is 13 pounds; 3 tablespoons if it's in the 14- to 15-pound range.
Three days before you plan to roast the turkey, put salt, rosemary, thyme, sage, mustard seeds, and pepper in a spice grinder and pulse together until they form a fine powder.
Rinse turkey and pat dry. Sprinkle outside of turkey all over with two-thirds of spice mixture, concentrating on breast and thighs. Toss remaining spices into cavity. Cover turkey with plastic wrap and chill in refrigerator 3 days. For extra-crisp skin, remove plastic wrap the night before roasting.
To roast, preheat oven to 425°. Set a V-shaped roasting rack into a large roasting pan and set aside. Gently separate skin from breast meat on both sides so that you can get your hand all the way in, being careful not to tear the skin. Rub 3 tablespoons butter onto breast meat on both sides. Brush skin all over with 2 tablespoons melted butter. Put apple and onion pieces in turkey cavity. Set turkey, breast side down, onto roasting rack. Pour broth and cider into bottom of pan and put in oven. Roast 45 minutes, basting occasionally. Flip bird over; then roast, basting occasionally, until thickest part of breast to the bone reaches 160° on an instant-read thermometer, another 1-¼ to 1-¾ hours, depending on size of bird.
Tip turkey to drain cavity juices, and transfer to a cutting board or serving platter. Tent with foil and let sit 30 minutes while you make gravy. Garnish turkey with apples and lemon leaves if you like; then carve and serve.