Coarsely grind the star anise, peppercorns, cloves, coriander seeds and fennel seeds then transfer to small bowl.
Grind the cinnamon stick and add to bowl. Mix in the Droitwich Pure Salt and stir in the orange peel.
Place the turkey into a roasting bag and sprinkle the bird inside and out with the salt mix then close the bag. Place it on baking sheet; refrigerate for 18 to 24 hours.
Preheat oven to 180C/350F/gas mark 4.
Mix the spring onions, orange, ginger, star anise and cinnamon.
Remove turkey from bag and divide chopped onion mixture between main and neck cavities. Place turkey on rack and set in large roasting pan.
Spread butter all over the turkey and pour 480ml of turkey stock into the pan.
Roast turkey according to size of bird and instructions (around 15-20 minutes per pound), basting with the pan juices every 45 minutes, adding stock or water to the pan by the cupful if dry, and tenting turkey loosely with foil if browning too quickly.
During the last half hour of cooking, mix the soy sauce and molasses in small bowl and brush on top of the turkey to glaze.
Once cooked, remove the turkey from the oven and leave to rest.
Pour the pan juices into measuring jug. Spoon off fat from surface, reserving 120ml fat to one side.
Add enough turkey stock to pan juices to measure 1.25l.
Place the roasting pan on medium heat; add the reserved turkey fat and 75g flour. Whisk for around 2 minutes until the roux is light brown. Whisk in the sherry, then stock mixture. Bring to boil, scraping up browned bits and whisking to blend.
Boil until gravy is thick enough to coat spoon, about 8 minutes.
Whisk in 1 tbsp of soy sauce and season well.