Wash and soak rice and udad dal in water, separately for 3 to 4 hours.
Drain and grind the udad dal with little water to a smooth paste and keep it aside.
Grind rice alongwith the cooked rice with little water into a smooth paste.
Mix udad dal and rice paste in a deep vessel.
Cover and keep the batter to ferment for six to eight hours in a warm place.
After fermentation, add salt to the batter, mix well and keep it aside.
Wash the jackfruit leaves and wipe them dry.
Fold each leaf in the shape of a cone and secure the ends with the help of tooth picks (Watch the video below for better understanding).
Pour the idli batter into each cone and place each cone in a steel glass.
Boil water in a steamer.
Keep a plate in the steamer and place all the steel glasses with the cone on the plate.
Cover the steamer and steam the idlis for 10 to 12 minutes.
Once the idlis are steamed, remove the cones from the glass and cool it for a few minutes.
Peel the leaves and serve cone idlis with chutney/ sambhar.