Clean well the fish, retaining the head and tail. Fillet it, slicing the flesh upwards from stomach to within 1 inch of dorsal fin. Cut flesh into 14 pieces, each 2 x 2/3 inch in size.
Mix fish pieces with marinade ingredients and keep aside 20 minutes.
Cut away the central bone from fish, leaving head and tail connected by dorsal fin. Make a vertical cut underneath mouth of fish and press head lightly so that it will stand upright. Place on heatproof dish and sprinkle with salt.
Alternately arrange fish slices, ham and mushrooms around both sides of fish-bone.
Place in steamer and steam over high heat; 8 minutes. Carefully drain and reserve cooking juices, without dis-arranging the ingredients.
Bring ½ cup of the cooking juices to the boil. Thicken with cornstarch-paste and pour over fish.
Heat 2 tablespoons oil till very hot; pour over fish. Garnish with coriander leaves and serve hot.
