Pour drippings from roasting pan into a fat separator and set aside. Place pan on 2 burners over medium-high heat. When pan is hot, pour in wine, scraping up brown bits with a wooden spoon. Pour in defatted drippings (use only 2 tablespoons of those from dry-brined bird) and 2 cups stock; bring to a boil.
Combine remaining 1/2 cup stock and cornstarch in a small jar, seal it, and shake to combine. Pour cornstarch mixture into boiling mixture in pan and boil until thickened, 2 to 3 minutes. Pour through a fine sieve into a bowl. Reheat when ready to serve. Before serving, season with salt and pepper.
