In a small bowl, combine 2 teaspoons salt, the garlic powder, onion powder, sage and pepper. Use to generously season the turkey wings on all sides and use any extra to season the carrots, celery and onion.
Place the turkey wings and vegetables in a Dutch oven and bake, uncovered, 1 hour and 15 minutes.
Transfer the Dutch oven to the stovetop on medium-high heat. Add the stock and bay leaves. Use a wooden spoon to break up any browned bits on the bottom of the pan. Bring to a low boil, reduce the heat to low and cover. Simmer 1 1/2 hours.
Remove the turkey wings and use a mesh strainer to separate the vegetables from the broth. Use a spoon to press out any liquid from the vegetables. Use a gravy fat separator (optional, but I like to do this step because I find the extra fat can cause the gravy to separate) or skim off the excess fat.
In the same Dutch oven, melt the butter over medium heat. Stir in the flour and cook until it starts to turn golden brown, 2 to 3 minutes. Slowly whisk in the reserved broth, sherry and Worcestershire. Simmer until it thickens, 8 to 10 minutes. Taste and add salt and pepper if necessary. If you have any lumps, pass through a fine mesh sieve. Let cool completely and refrigerate or freeze until use.
Reheating Instructions: You may need to add a few tablespoons of stock and whisk vigorously to thin out the gravy.
I removed the skin from the turkey wings and shredded the meat, then tossed with BBQ sauce. Delicious!