Prepare the brine for the turkey by simmering the 2 quarts of water.
Whisk in the sugar and 1 cup of salt, until well combined.
Add the peppercorn, sliced tart apple, and a few sprigs of rosemary. Bring to a simmer for 15 minutes.
Allow the brine to cool (or add a few bits of ice) before submerging the turkey and allowing it to brine 10-12 hours but preferably for 24 hours.
Remove the turkey from the brine, drain, and pat dry.
Stuff the turkey with sweet apples, celery, onion, sage, rosemary, and thyme.
Brush on melted butter over the outside of the turkey before seasoning with the remaining 2 tablespoons of salt, ground black pepper, and garlic (the butter helps the seasonings stick).
Tie the legs and wings with butcher twine or just tuck the wings underneath the bird so they don't burn.
Stock the smoker with wood (chips, chunks, pellet, or whatever your smoker is designed for) and fill the steam pot with water.
Smoke the turkey for about 6 hours at 275°F/135°C, until the internal temperature reaches 165 degrees at the breast and 175°F/80°C degrees at the thighs. Rotate the turkey within the smoker as needed, so the skin doesn’t get too dark. (please see page 3 of this document under “cook” for better instructions on how to smoke the turkey)
Allow the turkey to rest for 30-40 minutes before carving.