Preheat oven to 425°F/220°C.

Arrange the carrots, celery, onion and garlic in the bottom of a high-sided roasting pan.

Spatchcock the turkey, by removing the backbone and lay flat. For step by step  instructions with photos click here, lay bone-side down onto the vegetables. Set aside while you make the glaze.

To a saucepan add the orange juice, cranberry juice, soy sauce, spices and honey. Heat over medium heat and stir while it simmers and thickens. 

Mix 2 teaspoons cranberry juice with the corn starch, whisk into the glaze and simmer until thick. Pour half of the glaze into a bowl and brush all over the skin of the turkey. Do not use the glaze that was brushed onto the raw turkey for the cooked turkey. (see note) Place the orange slices on top of turkey. Keep the other half of the glaze separate from the raw meat to brush over the cooked turkey.

Pour the stock into the bottom of the pan to cover the vegetables.

Place the turkey in the oven and roast for 40 minutes. Brush more glaze over the turkey and rotate the pan. Roast for 50 minutes more until a meat thermometer reads 165°F when inserted into the thickest part of the leg.

Remove the carrots and celery from the pan drippings set aside to serve later. Add the onions and garlic to a blender. 

Skim off as much fat as you can from the juices, or use a fat separator. Strain the juices and add to the blender, blend until smooth. Transfer to a saucepan over medium heat. 

Add 1 tablespoon of corn starch to a bowl and stir in 1 tablespoon chicken stock. Whisk this into the gravy and simmer until thickened.