Remove and reserve giblets and neck from turkey. Trim excess fat. Tie ends of legs together with twine. Starting at the neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between skin and meat. Combine 1/4 cup chopped shallots, butter, 1 tablespoon chopped sage, 1 teaspoon salt, and 1 teaspoon pepper. Rub butter mixture under loosened skin over breast and drumsticks. Stuff 1/2 cup onion, 1/2 cup carrot, 1/2 cup celery, and 3 sage sprigs into body cavity. Lift wing tips up and over back; tuck under turkey. Place turkey, breast side up, on a roasting pan. Pour 1 cup water and broth into pan. Bake at 450° for 30 minutes.
Reduce oven temperature to 350° (do not remove turkey from oven). Bake turkey at 350° for 1 1/2 hours or until thermometer inserted into meaty part of thigh registers 165°. Remove turkey from oven; let stand 30 minutes. Remove and discard skin.
Combine reserved giblets, neck, remaining 1/2 cup onion, remaining 1/2 cup carrots, remaining 1/2 cup celery, remaining 1 sage sprig, and remaining 5 cups water in a large saucepan; bring to a boil. Reduce heat, and simmer until liquid is reduced to 2 cups (about 1 1/2 hours). Strain mixture through a sieve, reserving stock. Discard solids.
Place a zip-top plastic bag inside a 2-cup glass measure. Pour turkey drippings into bag; let stand 10 minutes (fat will rise to the top). Seal bag; carefully snip off 1 bottom corner of bag. Drain drippings into a measuring cup, stopping before fat layer reaches opening.
Place giblet stock in a small bowl. Add enough drippings to measure 4 cups. Discard remaining drippings. Weigh or lightly spoon flour into a dry measuring cup; level with a knife. Add flour to drippings mixture; stir well with a whisk.
Heat oil in a medium saucepan over medium heat. Add 1 cup sliced shallots to pan; cook 5 minutes or until lightly browned. Stir in giblet mixture and remaining 1/4 teaspoon salt; bring to a boil. Cook 2 minutes or until thickened, stirring constantly. Stir in remaining 1 tablespoon chopped sage and remaining 1/4 teaspoon pepper.
Wine note: In this dish, turkey's subtle flavor is given a bit more punch with sage and shallots. Both the herb and the onion flavors (as well as the turkey itself) are complemented by a smooth, earthy pinot noir. Try Cambria's Bench Break Vineyard Pinot Noir 2006 from California's Santa Maria Valley (about $25). —Karen MacNeil