Soak 10 wooden skewers in water for 30 minutes to prevent burning.
In a food processor, finely chop the onion, garlic, ginger, lemon juice and rind, coriander, cumin and garam masala. Stir in the yoghurt and salt.
Thread 4-5 chicken cubes onto each skewer and place in a large shallow dish. Coat the skewers with the spice mixture. Marinate for several hours or overnight, covered, in the refrigerator.
Cook the skewers in batches on a barbecue or char-grill pan, or until a hot grill for 3-4 minutes on each side, or until golden brown and cooked.