Preheat oven to 200C. Rinse the turkey cavity under cold running water. Pat dry with paper towel inside and out.
Cut lemon into wedges and place in cavity with rosemary. Tuck wings under turkey and tie legs together with kitchen string.
Place the turkey on a rack in a deep roasting pan, rub with 1 tsp of the extra virgin olive oil and season with salt and pepper. Pour 2 cups of water into the bottom of the pan.
Cover turkey with foil and roast for 30 minutes.
Reduce heat to 180C and roast for a further 30 minutes.
Remove foil from turkey and roast for 45 – 60 minutes more until skin is golden and juices run clear when a skewer is inserted into the thigh. Re-cover if browning too quickly.
Remove from oven and rest for 20 minutes in the pan before moving to a serving platter. Reserve the roasting pan juices to make the gravy.
While the turkey is roasting heat another 1 tsp of the extra virgin olive oil in a frying pan over medium heat. Add the onion and garlic and cook for 5 minutes until soft and translucent. Stir through pistachios and 1/4 cup of the dried cranberries. Set aside to cool slightly.
Place 1 cup of the couscous into a large bowl. Heat 1/2 cup of the orange juice until warmed through, combine with 1/2 cup of the boiling water and pour over couscous. Stir and cover for 5 minutes to absorb.
Fluff couscous with a fork and combine with the onion mixture, egg, orange zest and 3/4 cup of the parsley. Season with salt and pepper, spoon into a baking dish sprayed with cooking oil spray and cover with a lid or foil.
Place stuffing in the oven as soon as you remove the turkey and bake for 30 minutes while turkey rests and you prepare the gravy. If your oven is large enough you can also bake the stuffing with the turkey for the final 30 minutes of roasting.
Place roasting pan with reserved juices over medium heat on the stove (you can transfer juices to a saucepan if you prefer). Add the flour to the pan and whisk well to combine. Cook, stirring, for 2 minutes or until the mixture starts to bubble.
Gradually whisk in the stock followed by the cranberry sauce and simmer, uncovered, stirring occasionally, for 5 minutes until thickened. Taste and season with salt and pepper.
Carve the turkey, dividing into 100g portions of meat per person. Serve turkey with stuffing, gravy and couscous salad.
Store extra turkey, covered, in the fridge for 3 days or wrap well and freeze for up to 3 months.
If your turkey is frozen, ensure it has fully thawed before cooking. A 3.5 kg turkey will take approximately 2-3 days to thaw in the fridge.
Check the cavity of the turkey before cooking, some turkeys have the neck inside.