Soak the dal overnight. Grind the soaked dal to a smooth paste in a blender.Wash Idli rava and mix it with urad dal paste. Mix the batter well in a large steel bowl. Place the batter in a warm place(say, oven) to ferment overnight. Keep a big plate underneath the bowl, because fermentation may cause the batter to overflow.
Mix the fermented batter thoroghly and add salt to taste. Grease the molds of idli stand with ghee. Pour the required amount of batter in each of the molds of idli stand and steam it in a pressure cooker. Allow it to steam on high for 5 to 7 min. Then simmer it and wait for 5 more minutes. Then carefully uncover the cooker and remove the stand. Transfer the idlis to a serving dish and serve it with coconut chutney.
If the above traditional method is hassle for you then check this method. This recipe was contributed by my cousin, who is a neonatologist(obviously, a busy person). The method is very simple. All you need is fermented batter, microwave and a micro egg poachers(available in any stores and is less than a $3.00). Apply oil on both sides of the molds. Pour the batter in the molds and microwave it . It will be ready within a few minutes. No hassle of washing cooker and idli stand. Doesn't it sound easy? Well try it out.