Pre-heat the oven to 550 degrees. Heat a roasting pan large enough to hold the bird in the warming oven.
Pull bird out of brine and rinse extremely well. Pat dry and rub canola oil all over and inside the bird and season with black pepper. Place turkey into the hot roasting pan and return to the oven. Let brown on top, about 20 to 30 minutes. Place foil on top of the bird and reduce oven to 325 degrees. Cook for 1 1/2 to 2 hours, or until juices run clear after puncturing between leg and breast. Let bird rest 10 minutes before slicing.
Drain off all but 2 tablespoons of fat (reserve the rest). Place roasting pan on a high burner and saute garlic, shiitakes, and leeks until soft, about 5 to 8 minutes. Season and deglaze with white wine and reduce by 50 percent. Add stock and reduce by 25 percent. Check for flavor. Keep sauce hot. Do not wash roasting pan. Place a mound of yams in the middle of a platter and surround with sliced turkey. Serve sauce in a small sauceboat.
In a large bowl, mix together the yams, sugar, juice, zest, ginger, five spice powder, and butter. Season. Place in a preheated 325 degrees oven (when you turn the oven down for the turkey) and bake for 1 1/2 to hours, or until potatoes or soft.