Place the chicken in a large, non-metallic dish. To make the marinade, mix together all the remaining ingredients, season well and pour over the chicken. Cover and chill for 24–48 hours.
When ready to cook, allow the chicken to come to room temperature.
Meanwhile slice the onions into thin rings and place in a large mixing bowl. Season with salt and pepper and squeeze over the juice of the lemons. Cover and allow to stand for 30 minutes before tossing and serving with the kebabs.
Divide the chicken pieces between 8–12 metal skewers, place on a lightly oiled grill rack in a single layer and lightly brush with sunflower oil.
Place the kebabs under a medium-hot grill and cook for 3–4 minutes on each side, or until cooked through. Alternatively, cook in a preheated oven at 200°C (400°F), Gas Mark 6 for 8–10 minutes. Serve with the red onion salad and lime halves for squeezing.