1. Cut onions up into 6 wedges.
2. In a large bowl, grate the peel of one lemon, then juice both lemons and pour into bowl.
3. Add garlic, olive oil, salt and pepper.
4. Crush the rosemary in your hands and sprinkle on top.
5. Add the lamb and onions and toss lightly to coat.
6. Let mixture marinate for at least several hours, or overnight.
7. Soak 6 wooden skewers in cold water for an hour, then thread lamb and onions.
8. Barbecue for 15 minutes or until cooked, basting with reserved marinade.
Serve with pitta bread, tzatziki (yogurt cucumber) sauce and garden salad.