In a 5- to 6-qt. pan, combine giblets, neck, onions, carrots, celery, and 1/2 cup broth. Cook, covered, over medium-high heat, 20 minutes. Uncover; cook over high heat, stirring often as liquid evaporates, until giblets and vegetables are browned and browned bits stick to pan, 5 to 8 minutes. Add another 1/2 cup broth and stir to loosen browned bits. Cook and brown, uncovered, as before.
Add remaining 3 1/2 cups broth, 2 cups Zinfandel, the orange zest, and pepper to pan. Cover and simmer over low heat for 1 to 1 1/2 hours.
Add apple mixture from cavity of Wine-Smoked Turkey; bring to a boil. Lower heat and simmer, covered, 5 minutes.
Pour broth mixture through a fine strainer into a bowl. Discard contents of strainer. Measure broth; if needed, add enough turkey pan juices to make 5 1/2 cups. In pan, mix cornstarch with 1/4 cup water and remaining 3/4 cup wine. Stir in broth mixture and cook, stirring, over high heat until boiling, about 5 minutes. Season with salt to taste.
Note: Nutritional analysis is per 1/3-cup serving.