To make the first marinade, put the paste, chopped ginger, vinegar, and oil in a large shallow dish. Season with salt and mix well.
Add the chops and spread the marinade evenly over to coat. Cover and allow to marinate in the refrigerator for about 6 hours.
Mix the yoghurt with all the other ingredients for the second marinade in a large shallow dish.
Remove the meat from the first marinade, wiping off any excess moisture from the first marinade, and add the meat to the second marinade. Cover and allow to marinate in the refrigerator for a further 3 hours.
Prepare a tandoor or charcoal grill for moderate heat, or alternatively preheat the grill (broiler) to medium. Thread the chops onto metal skewers, leaving 2.5cm / 1-inch between them. Make sure they do not fall off the skewers.
Roast in a moderately hot tandoor, over a charcoal grill, or under the hot grill for about 10 minutes. Remove the skewers from the heat and hang up to drain. Put the skewers into a dish and baste with the melted butter, then roast for a further 5 minutes, or until cooked. Serve hot.