1. Preheat oven 200 degrees fan.
2. Coarsely crush the black peppercorns with a pestle and mortar. Add the dried chillies and crush a little more, but not too finely.
3. Make a marinade by mixing the olive oil, lemon juice, minced chilli (optional), garlic, black pepper, crushed chillies chopped rosemary and sea salt.
4. Put the chicken in a shallow dish, pour over the marinade, and turn the chicken once or twice to coat. Cover with cling film and leave to marinate for at least 1 hour turning occasionally.
5. Transfer the chicken to a roasting dish, place chicken in the oven and reduce to 180 degrees. Cook for 1 hour or until cooked.