Preparation

Dry-brine the turkey

• In a small bowl, combine the salt, pepper, celery seed, and coriander. Remove the neck, tail, and giblets from the turkey and reserve for the broth. Remove any plastic parts such as pop-up timers and leg ties. Pat dry with paper towels, and place breast side up on a wire rack in a large flameproof roasting pan.
• Using your fingers, gently separate the skin from the meat, taking care not to tear the skin. Spread half of the salt rub under the skin, massaging it directly onto the meat. Massage the remaining rub all over the skin and in the cavity.
• Refrigerate uncovered for at least 8 hours and up to 24 hours.

Make the turkey broth

• Position a rack in the center of the oven and heat the oven to 400°F. On a small rimmed baking sheet, toss the turkey neck, tail, giblets (excluding the liver), and onion with the oil and arrange in a single layer. Roast, flipping once, until well browned, about 40 minutes. Transfer to a heavy-duty 3- to 4-quart pot. Pour 1 cup of the chicken broth onto the hot baking sheet and scrape up any browned bits with a wooden spatula; transfer to the pot. Add the remaining broth and bring to a boil; lower the heat and simmer until reduced by half, about 45 minutes. Strain through a fine-mesh sieve; discard the solids. You should have about 2 cups.

Make the flavored butter

• In a small bowl, with a fork, mash the butter with the garlic, citrus zests, rosemary, and sage until thoroughly incorporated.

Roast the turkey

• Remove the turkey from the refrigerator and let sit at room temperature for 1 to 2 hours.
• Reserve 1/4 cup of the butter. Rub the rest under the skin of the breast and thighs. Tuck the wings behind the neck and tie the legs together with twine.
• Position a rack in the center of the oven, and heat the oven to 350°F.
• Roast the turkey uncovered, basting every 30 minutes, until an instant-read thermometer in the thickest part of the thigh registers 170°F, about 2 hours. (If the breast becomes too dark, cover with foil.) Remove from the oven, transfer to a carving board, and tent with foil. Let rest at least 30 minutes and up to 2 hours.

Make the gravy

• Pour the drippings from the roasting pan into a fat separator; allow the fat to rise to the top, about 5 minutes, and discard.
• Add the gin to the roasting pan. Boil over medium-high heat, scraping up any browned bits from the bottom of the pan, until reduced to 1/2 cup, about 2 minutes. Strain through a medium-mesh sieve set over a 3- to 4-quart heavy-duty saucepan. Add the defatted pan drippings and the broth and bring to a boil. Lower the heat to a simmer and reduce to 2 cups.
• Using a fork, mash the flour with the reserved herb butter until thoroughly combined. Whisk 1 Tbs. of the butter mixture into the broth mixture and continue adding, 1 Tbs. at a time, until the gravy has thickened to your desired consistency.
• Carve the turkey and serve with the gravy.

Make Ahead Tips

The turkey broth can be made up to 1 day ahead. Keep refrigerated.

The flavored butter can be made up to 5 days ahead. Keep refrigerated and return to room temperature before using.

The roasted turkey can rest at room temperature up to 2 hours before carving and serving.