1 (10 to 20 lb.) natural turkey (giblets and neck removed)
2 cups kosher salt, plus more to taste
1 cup sugar
8 tbsp. unsalted butter, softened
10 cloves garlic
20 fresh sage leaves, half finely chopped
Freshly ground black pepper, to taste
Toast whole sage leaves in a skillet over medium-high heat for 2 minutes. Put sage into a large pot with 2 cups salt, sugar, and 2 quarts water. Bring to a boil, remove from heat, and stir in 6 quarts water; let cool completely.
Put brine and turkey into a brining bag; seal and refrigerate for 8 hours or overnight.
Preheat oven to 325°. Mix chopped sage, butter, garlic, salt, and pepper to form a compound butter; set aside. Remove turkey from brine; pat dry. Lift skin at neck of bird; cut and remove wishbone (make a wish and discard, if you like). Place turkey on a rack in a roasting pan, breast side up, and tuck wings under the body. Rub turkey all over with half of compound butter; rub remaining compound butter under skin of turkey. Tie legs together with butcher’s twine. Roast turkey, basting every 30 minutes, until deep golden brown and a thermometer inserted in the thickest part of the thigh (not touching bone) registers 165°, 2 1⁄2–3 hours. Let turkey rest for 20 minutes before carving (see How to Carve a Turkey).