For the spicy chicken, mix all of the ingredients for the spicy chicken, apart from the olive oil, together in a resealable food bag or non-metallic bowl and shake or mix to ensure the chicken is completely coated in the other ingredients. Transfer to the fridge to marinade for at least three hours or overnight.
When ready to cook the chicken, heat a griddle pan until hot, then remove the chicken from the marinade and rub all over with the olive oil. Place on the griddle and cook for about 15 minutes for breast, 20 minutes for thighs, turning once or twice, or until cooked through (juices should run clear with no trace of blood when the thickest part of the chicken is pierced with a skewer).
For the vegetable ragu, heat the olive oil in a wide pan over a medium heat and fry the garlic for one minute until aromatic. Add the aubergine, onion, courgettes and red pepper to the pan and fry for 20 minutes, stirring every few minutes, or until the vegetables are softened and golden-brown in places.
Stir in the tomatoes, sugar, balsamic vinegar and oregano and cook for a further 20 minutes until reduced to a thick, rich consistency.
In a small bowl mix together the parsley and lemon zest then stir this through the vegetables and serve at once with the griddled chicken alongside.