Black yam cake has a similar texture to beanpaste and consists of more than 90% water. Made from konnyaku yams, it helps cleanse the digestive system. Yam cake is valued more for its texture than flavour and is used in various dishes. PLEASE NOTE A KONNYAKU BLOCK IS NEEDED NOT POWDER. THE ZAAR SYSTEM WILL ONLY ALLOW ME THE POWDER. This is a common way of serving the cake. It is highly valued for its lack of fat, sugar and its ability to fill you up without huge amounts of calories. Cooking time includes marinating.