Prepare Idli Batter : Soak urad dal with fenugreek seeds and rice separately for 4–6 hours. Grind urad dal to a smooth batter and rice to a slightly coarse texture. Mix together, add salt, and ferment overnight.
Steam Idlis ; Grease idli molds and pour the fermented batter. Steam in an idli steamer or pressure cooker (without whistle) for 10–12 minutes until firm and fluffy.
Prepare Coconut Chutney : Grind coconut, roasted chana dal, green chilies, ginger, salt, and water to a smooth paste. Temper with mustard seeds, dried red chili, and curry leaves in hot oil.
Prepare Sambar : Cook toor dal until soft and mash. In a pan, cook vegetables with turmeric and sambar powder. Add cooked dal, tamarind paste, and water. Simmer for 10–15 minutes. Temper with mustard seeds, cumin seeds, dried red chilies, and curry leaves in hot oil, then mix into the sambar.