Remove and discard leg truss from turkey. Pull off and discard any lumps of fat. Remove giblets and neck; save for gravy if desired. Rinse turkey inside and out; pat dry. If using spice rub, rub it generously over skin and inside both neck and body cavities. Brush bird with enough oil to coat.
Place turkey, breast up, on a V-shaped rack in a 12- by 17-inch roasting pan (pan should be large enough that turkey fits inside).
Roast in a 325° regular or convection oven, basting occasionally with oil, or pan drippings if using spice rub, until a thermometer inserted through thickest part of breast to the bone registers 160°, 2 to 3 hours.
Transfer turkey to a platter. Let rest in a warm place at least 30 minutes, then carve. When you remove the legs, if meat around thigh joints is still too pink, cut drumsticks from thighs and put thighs in a shallow pan in a 450° oven until no longer pink, 10 to 15 minutes.
Spice Rub: In a 6- to 8-inch frying pan over medium heat, stir 1 tablespoon fennel seeds until lightly browned, about 1 minute. Pour into a blender and whirl until finely ground. Add 3/4 teaspoon hot chili flakes and whirl until coarsely ground. Pour into a small bowl and mix with 3 tablespoons Madras or regular curry powder, 1 1/2 tablespoons sugar, 1 tablespoon paprika, and 1 1/2 tablespoons salt. Makes about 1/2 cup.
Nutritional analysis per 1/4 pound boned cooked turkey with skin, based on percentages of white and dark meat in an average bird.