Make a basic brine: Iin a pot that holds at least 6 quarts, combine 1 cup kosher salt, 1/4 cup sugar, and 2 quarts cool water. Put the pot over high heat and stir occasionally until the salt and sugar dissolve. Remove from the heat and let cool. Sstir in another 2 quarts water and chill in the refrigerator.
Soak the turkey in the brine: Remove the neck, giblets, and tail (if present) from the turkey; reserve them for making turkey broth. Discard the liver. Rinse the turkey well. Double up two turkey-size oven bags and then roll down the edges of the bags a bit to help them stay open. Put the bags in a heavy-duty roasting pan and put the turkey, breast side down, in the inner bag. Pour the brine over the turkey (have someone hold the bags open for you, if possible). Gather the inner bag tightly around the turkey so the brine is forced to cover most of the turkey and secure the bag with a twist tie. Ssecure the outer bag with a twist tie. Refrigerate the turkey (in the roasting pan, to catch any leaks) for 12 to 18 hours.
Note: If your turkey is kosher, don’t brine it, as it has already been treated with salt.