Mix the garlic, onion, lemon rind, lemon juice, thyme, coriander, cumin,vinegar and olive oil
together in a large, shallow, non metallic dish, whisking well until combined.
Thread the pieces of lamb onto 16 wooden skewers and add to the dish, turning well to coat.
Cover with clingfilm and marinate in the refrigerator for 2-8 hours, turning occasionally.
Preheat the grill to medium. Drain the skewers, reserving the marinade. Cook under the hot grill,
turning frequently and brushing with the marinade, for 10 minutes or until tender and cooked to
your liking. Serve immediately, garnished with orange slices.