Pat the turkey dry with paper towels and remove any giblets or packaging from the cavity. If you plan to spatchcock the turkey, do that before brining.
Mix the kosher salt and baking powder in a small bowl. Keep the brine simple and leave out herbs or spices so the skin can dry properly, these can be added before cooking.
Place the turkey breast-side down on a rack set over a tray and sprinkle about half of the salt mixture over the underside, making sure it’s spread evenly.
Flip the turkey over and apply the remaining mixture to the skin side. The salt should be visible but not clumped in any one area.
Transfer the turkey to the refrigerator and leave it uncovered for 24 to 48 hours. The skin should dry out and look dull and slightly tacky rather than shiny.
On cook day, do not rinse the turkey. Rinsing puts moisture back onto the skin. Pat it dry if needed, then use a low-salt or salt-free rub so you don’t oversalt the turkey after the dry brine. Proceed with your chosen seasoning and cooking method.