Using a sharp knife, cut the lamb into thin slices and place in a large baking bowl.
Stir together the curry paste, coconut milk, garlic, chili spice and cumin in a baking bowl. Pour over the lamb, turn well to coat the other side, cover and marinate for 30 minutes.
Meanwhile, cook the satay sauce. Heat the oil in a large wok and sauté the onions for 5 min.
Simmer for another 5 min on reduced heat.
Mix in the peanut butter, tomato puree, lime juice and water.
Thread the lamb onto the wooden skewers. Reserve the marinade.
Grill the lamb skewers under a hot broiler for 6-8 min, turning once to the other side.
Add the rest of the marinade to the wok, bring to the boil and cook for 5 minutes. Serve the lamb kebabs together with the satay sauce.
Soak them in cold water so that they do not start to burn.