Soak the urad dal and fenugreek seeds in water. Soak rice in boiled water. After 3 hours, drain urad dal as well as rice separately. Grind urad dal and fenugreek into a smooth paste with little water. Grind rice into a coarse paste, sprinkling little water only to the extent required. Mix the dal and rice pastes by hand, adding salt to taste. Leave the batter overnight so that it will ferment. Laddle the batter on the idli stand and steam. Serve hot with sambar or chutney.