Place the ribs on a baking tray and sprinkle generously with salt. Blend the herb cube with the mustard, chilli powder and vinegar. Add the sugar and stir in the boiling water. Bring the mixture to simmering point and boil gently for 3-4 minutes or until the sugar has dissolved. Cut away the outer skin, remove the core from the pineapple and cut into triangles. Spread amongst the tray of spare ribs. Pour the liquid over the top and place in a preheated oven 170?C, 325F, gas mark 3, for 2 hours or until thoroughly cooked. Turn the ribs 3 or 4 times during the cooking. NOTES : The juice of fresh pineapple helps to tenderise the spare ribs as well as adding flavour and succulence to the dish. Serve the ribs with jacket potatoes or deep-fried potato skins with Waitrose Sour Cream and Chive Dressing.