In a small bowl, combine 2 tbsp dried sage, 1 tbsp dried thyme, 1 tbsp dried rosemary, 1 tbsp garlic powder, 1 tbsp onion powder, 1 tbsp sea salt, 2 tsp freshly ground black pepper, 1 tsp smoked paprika and 1/2 tsp cayenne pepper (optional).
Whisk together until evenly blended and the mixture looks uniform.
Pat the turkey dry with kitchen paper then rub about 2–3 tbsp of the seasoning all over, making sure to get into any nooks and under the skin where possible.
For best flavour, chill the seasoned turkey in the fridge overnight (optional), or let it rest for at least 1 hour before roasting.
When ready, preheat the oven to 160 °C (gas mark 3).
Roast the turkey until a meat thermometer inserted into the thickest part of the thigh (avoiding the bone) reads 74 °C, about 35–45 minutes per kg.
Store any leftover seasoning in an airtight container in a cool, dark place for up to 6 months.