Melt the turkey fat and/or butter in a medium saucepan over medium heat until it starts to bubble.
Sprinkle in the flour and whisk constantly until smooth, about 30 seconds.
Keep whisking and cook the roux for 3 to 5 minutes, until it smells nutty and turns light golden brown, like peanut butter.
Slowly pour in about 1 cup of the warm drippings and broth while whisking hard. It will thicken into a paste. Add the rest 1 cup at a time, whisking smooth after each addition.
Stir in the soy sauce, thyme and pepper. Simmer gently for 5 to 8 minutes, stirring often, until the gravy coats the back of a spoon.
Taste, then add salt a pinch at a time. Strain through a fine-mesh sieve for extra-smooth gravy if you like, and serve hot over mashed potatoes.
No drippings? Use 1/2 cup unsalted butter and 4 cups low-sodium turkey broth. A teaspoon of bouillon paste adds roasted flavor.Gravy thickens as it cools, so take it off the heat when it is slightly looser than you want.Thickness guide per 1 cup liquid: 1 tbsp each fat and flour (thin), 2 tbsp (medium, this recipe), 3 tbsp (thick).Store in the fridge up to 3 to 4 days or freeze 2 to 3 months. Reheat on the stove, whisking, until steaming and 165°F (74°C).Nutrition is an estimate and varies with your drippings.