1. Trim any excess fat from the meat.
2. Cut into 2.5 cm (1 inch) cubes and keep aside in a bowl.
3. In a blender or food processor, blend the chopped garlic, ginger, cumin seeds, black peppercorns, coriander seeds, chili pd, sugar, salt and papaya to a smooth paste.
4. Add the vinegar and grind for another minute.
5. Then add the Worcestershire sauce and the oil and mix all the ingredients.
6. Add the ground mixture to the meat and coat thoroughly.
7. Cover and place in refrigerator to marinate for 10 hours.
8. Stir from time to time.
9. Prepare the barbecue for heat the grill.
10. Thread a few pieces of meat on to each skewer and cook, turning frequently, for about 15 minutes until the lamb is tender and well browned.
11. Remove from the skewers and serve without delay.