In a large pot, combine the kosher salt, brown sugar, black peppercorns, allspice berries, dried thyme, and dried rosemary.
Pour in 1 gallon of water, and if using, add 1 cup of apple cider or juice. Heat the mixture over medium heat.
Stir the brine until the salt and sugar are completely dissolved. Bring to a simmer, then remove from heat.
Allow the brine to cool completely to room temperature. To speed up the cooling process, you can add ice cubes or chill in the refrigerator.
Once cooled, place your turkey (cleaned and unwrapped) into your chosen brining container.
Pour the brine over the turkey, ensuring it is fully submerged. If necessary, add extra water to cover the bird completely.
Cover and refrigerate the turkey in the brine for 12 to 24 hours, depending on the size of the turkey.
After brining, remove the turkey from the solution, rinse under cold water, and pat dry before cooking.