Step 1

Place the turkey breast side down on a cutting board. Using sturdy kitchen shears, cut along one side of the backbone top to bottom. Repeat on the other side of the backbone, then remove and discard, or reserve for making stock. Open up the sides of the bird, flattening it as much as possible. Sprinkle with 2 teaspoons salt, then flip the turkey breast up, making sure the sides are splayed out, not folded under.

Step 2

Using the heel of your hand, press down firmly on the thickest part of the breast until the wishbone snaps. If desired, remove and discard the wing tips or reserve for making stock; alternatively, tuck the wings to the back. Sprinkle 1½ tablespoons salt evenly over the skin side of the turkey, then transfer skin side up to a rimmed baking sheet. Refrigerate, uncovered, for at least 2 hours or up to 18 hours.

Step 3

One hour before roasting, remove the turkey from the refrigerator and let stand at room temperature. Heat the oven to 425°F with a rack in the lowest position. In a large roasting pan, toss the carrots, celery, onion and rosemary; distribute in an even layer. Transfer the turkey to the pan, placing it breast up on top of the vegetables. Drizzle the oil over the turkey, and, using your hands or a brush, spread the oil so it fully coats the skin. Sprinkle lightly with pepper.

Step 4

When the turkey has stood at room temperature for 1 hour, add 1 cup water to the pan (do not pour the water over the bird) and transfer to the oven. Roast until an instant thermometer inserted into the thickest part of the breast reaches 165°F, about 1¾ hours for a 12-pound bird or about 2 hours for a 14-pounder.

Step 5

Remove from the oven and let the turkey rest in the roasting pan for at least 20 minutes. When ready to carve, transfer to a cutting board. If desired, strain contents of the roasting pan and use the drippings to make gravy.