Recipe Source: From my very old South Indian Cookery book - published in 1983 :))
Raw Rice - 2 cups
Whole Urad dal - 1 cup
Curd - 300 ml
Dry Ginger/Sukku - 1 inch piece powdered
Asafoetida - 2 tsp
Salt - to taste
Ghee - 1-2 tsp
Mustard - 1 tsp
Pepper, Cumin - 1 tbsp
Urad dal, Channa dal - 2 tbsp
Curry leaves - few
Green chillies(chopped) - 1 (optional)
Cashews - 15
Soak Urad dal and Raw rice separately for 2 hours.
Wash and completely drain water from rice and dry.
Grind rice in mixie to rawa like consistency without adding water.
Wash and grind Urad dal completely like how we grind for idli.
Mix both adding curd, dry ginger powder, asafoetida, salt and water to idli batter consistency.
Let it sit overnight for fermentation.
Next day, do tempering(heat ghee and fry all that is mentioned for tempering) and add to the fermented batter and mix well.
Grease cups with oil and pour the batter to 3/4 of the cup.
Steam for 10 minutes. If not cup, just pour it to the idli plates and steam.
Cool for few minutes.
Kanchipuram idli is ready to serve!