Preparing the Turkey

Place the turkey on a cutting board, ensuring it is dry by blotting with paper towels. Position the bird breast-side down with the legs facing towards you. Locate the backbone, a ridge running down the center, and using kitchen shears, cut along both sides of the backbone. Keep the backbone, as it can be used later for making stock or gravy.

Flip the turkey over, breast-side up, and spread the legs and thighs outward. Using the palms of your hands, press down firmly on the breastbone to break it, creating a flat, spatchcocked turkey. Position the legs outward and tuck the wingtips under the bird.

Dry Brining

Pat the turkey dry again if needed. Evenly sprinkle the coarse sea salt over both sides of the turkey. Refrigerate the turkey uncovered for at least 6 hours or overnight to dry brine, which will result in crisp skin upon roasting.

Preparing the Turkey for Roasting

Before roasting, remove the turkey from the refrigerator and allow it to come to room temperature for about an hour. Preheat the oven to 400°F (200°C, Fan Forced) and position the oven rack in the center.

Spread the chopped onions, carrots, and celery (if using) across a large roasting tray. Place a wire rack on top or alternatively, position the turkey directly above the vegetables, using the halved onions as a natural trivet.

In a bowl, prepare the compound butter by combining the softened butter with the Dijon mustard, garlic powder, sweet paprika, five-spice seasoning (if using), fresh thyme, and chopped sage. Mix thoroughly until the ingredients form a smooth, spreadable paste.

Loosen the skin over the turkey's breast and thighs, then generously rub the compound butter underneath the skin, making sure to coat it evenly. Spread the remaining butter over the surface of the turkey.

Roasting the Turkey

Place the turkey in the preheated oven. Roast until an instant-read thermometer inserted into the thickest part of the breast reads 150°F (65°C) – this is your pull temperature.

Remove the turkey from the oven and cover loosely with foil. Allow the turkey to rest for at least 30 minutes; during this time, the internal temperature will rise to the recommended 165°F (74°C) for the breast. For dark meat, check that the temperature reaches 175°F (80°C) in the thickest part of the thigh.

Carving and Serving

To carve, first remove the legs and thighs by cutting through the skin that joins them to the breast. The leg should detach easily. Then, remove the wings using the same technique.

Slice along one side of the breastbone to remove the breast meat, repeating on the other side. Separate the thighs from the drumsticks and carve the thigh meat into slices. Finally, slice the breast meat into thick slices at a slight angle.

Arrange the carved turkey on a platter. For a decorative touch, consider adding sliced oranges, bay leaves, and cranberries. Serve with your preferred sides.