Combine all brine ingredients, except ice water, in a stockpot, and bring to a boil. Stir to dissolve solids, then remove from heat, cool to room temperature, and refrigerate until thoroughly chilled.
48 hours before cooking, combine the brine and ice water in a clean container or plastic bag. Place thawed turkey breast side down in brine, cover, and refrigerate.
A few minutes before roasting, heat oven to 400 degrees F. Remove bird from brine and rinse inside and out with cold water. Discard brine. Place bird on roasting rack inside wide, low pan and pat dry with paper towels. Add steeped aromatics to cavity along with rosemary and sage. Tuck back wings and coat whole bird liberally with canola (or other neutral) oil.
Roast on lowest level of the oven at 500 degrees F. for 30 minutes. Remove from oven and cover breast with double layer of aluminum foil, insert probe thermometer into thickest part of the breast and return to oven, reducing temperature to 350 degrees F. Set thermometer alarm (if available) to 161 degrees F. A 14 to 16 pound bird should require a total of 2 to 2 1/2 hours of roasting. Let turkey rest, loosely covered for 15 minutes before carving.