In a large mixing bowl, combine the salt and pepper. Place the turkey legs in a large re-sealable bag and add the salt mixture. Shake around to coat the legs evenly and then seal bag and place in fridge overnight.
Preheat the oven to 300 degrees F. In a large Dutch oven over medium heat, add 1/4 cup duck fat. Remove the turkey legs from the bag and brush off excess salt. Add the turkey legs to the pot and brown all over, 3 to 4 minutes per side. Add the garlic and shallots and cook until fragrant, 2 to 3 minutes. Add the thyme, cloves, rosemary, star anise, fennel seeds, cinnamon, lemon peel and orange peel and then pour over the remaining duck fat so the legs are completely covered.
Bring to a gentle simmer (without boiling or frying), then remove from the heat, cover and place into the oven. Cook until the meat starts to fall off the bone, about 3 hours.
Place the legs on a baking sheet. Shred the meat and serve. Reserve the fat and use it to cook gravy, French fries or roasted potatoes. If making ahead of time, remove the pot from the oven and set aside to allow the turkey to cool in the fat. Once cooled, place in the refrigerator overnight to completely chill. To serve, remove the turkey from the fat and crisp in a dry pan to heat through.