Buttermilk-brined roast turkey

 INGREDIENTS

• 1 (4.5kg-6.3kg) turkey
• 2.8 litres buttermilk
• 128g fine sea salt (about 7 tbsp)

METHOD

1. Two to three days before you plan to cook, spatchcock the turkey: Put the turkey on a stable cutting board, breast-side down, and use heavy-duty kitchen shears to snip along both sides of the backbone to release it. You can start from the tail or neck end, whichever you prefer; just keep the blades of the scissors as close to the spine as possible. It helps to work incrementally, snipping a little on one side, then a little on the other, rather than completing one side entirely and then doing the second side without the advantage of the opposing pressure.
2. After removing the backbone, remove wingtips, neck and giblets, setting them all aside for stock and gravy.
3. Turn turkey over so breast faces up. Splay out its legs and press hard on the breastbone until you hear the cartilage pop and the bird lies completely flat.
4. Place a 7.5-litre extra-large resealable bag in a large bowl, stock pot or sink. Pour buttermilk and salt into bag and stir to dissolve salt. Place turkey in bag and seal carefully, expelling air. Double-bag the turkey as needed to prevent leakage, then squish the inner bag to distribute buttermilk all around the bird. Place it on a rimmed baking tray and refrigerate for 48 hours. Turn the bag every 12 hours so that every part of the turkey gets marinated.
5. Three hours before you plan to start cooking, remove the turkey from the plastic bag and scrape off as much buttermilk as you can without being obsessive, discarding buttermilk. Set the turkey on a rimmed baking tray and bring it to room temperature.
6. Position a rack in the upper third of the oven and heat to 180C fan-forced (200C conventional). Transfer turkey, breast-side up, to another rimmed baking tray lined with a wire rack or baking paper. Tuck thighs inward.
7. Place baking tray on the prepared oven rack and roast the turkey, occasionally rotating the pan 180 degrees, until an instant-read thermometer inserted into the deepest part of the breast registers 65C and the thickest part of the thigh without touching bone registers 75C, about 80 to 100 minutes, depending on size. (You may want to tent the breast or other hot spots with aluminium foil, if darkening too quickly.)
8. Transfer turkey to a cutting board or platter and allow to rest at least 20 minutes before carving.