Score several slits on each of the turkey drumsticks, using a sharp knife. Mix together the lemon zest, olive oil and curry powder, and rub it all over the turkey, working it well into the cuts. Season with salt and pepper and place in a shallow dish. Pour over 2 tbsp of the lemon juice, cover and leave in the fridge to marinate for 2–3 hours.
Preheat the oven to 190°C (gas 5). Toss the onions with the vegetable oil, then spread them over the base of an ovenproof dish. Place the turkey on top.
Roast for 30 minutes, then turn the turkey, spread with the butter and roast for a further 30 minutes. Turn the turkey drumsticks over again and baste with some of the cooking juices. Cook for a further 30 minutes or until the turkey is cooked through.
Place the turkey on a heated serving dish. Pour the remainder of the lemon juice into the cooking dish and scrape up the onions with a wooden spatula. Pour into a small pan, add the stock, heat gently, then stir in the crème fraîche and warm through.
Pour the sauce over the turkey and garnish with lemon slices and parsley. Grind some pepper coarsely over the top.
*Instead of large turkey drumsticks, use four large or eight regular-sized chicken drumsticks. Cook for about 40 minutes, or according to the instructions on the pack. *Serve with fluffy basmati rice – you could toss the cooked rice with the grated zest of one lemon and 2 tbsp chopped fresh parsley.