4 ribs of celery, roughly chopped (use leaves too)
1 onion, cut into chunks
4 cloves garlic, smashed with the back end of a knife
6 cups water
4 Tablespoons (1/4 cup) unsalted butter
1/4 cup all-purpose flour
2 cups turkey stock, strained and defatted
1/2 cup whole milk
1 teaspoon apple cider vinegar
kosher salt to taste (I used 1/2 teaspoon)
Preheat oven to 375 degrees F and in a large sauté or roasting pan (I use my large Dutch oven), roast (on a lower oven rack) turkey wings, celery, onion and garlic for 2 hours. Remove from the oven.
Add water and bring to a boil. Turn down heat and simmer on low for one hour, uncovered. Stock will reduce.
Strain the stock into a bowl with at least a 4 cup capacity. Place liquid into the refrigerator for at least 2 hours or overnight and remove the fat accumulated on top.
In a large sauté pan, melt unsalted butter and whisk in flour. Cook, whisking constantly over medium heat for two minutes. Whisk in turkey stock and cook until thickened. (The gravy should coat the back of a spoon.) Add milk, cider vinegar and salt to taste. If you cannot get your gravy as thick as you like it, you can always dissolve 1 teaspoon of cornstarch in one teaspoon of cold water and SLOWLY add it to the gravy while whisking.