In a pan or wok add a tsp of cooking oil and roast the onion slices till they become translucent. Transfer the onions. Next in the same pan add 2 tsp of oil, spices like coriander, cumin seeds, both the lentils, red chillies, cloves, cinnamon followed by curry leaves.
With constant sauteing roast all the spices. When the lentils turn little brown, switch off the pan. Throw in the grated coconut and tamarind. Let the coconut warm up a bit. Take everything in a mixer and grind to fine puree adding water as needed.
Next cook the vegetables with enough water, turmeric powder and salt. When the veggies turn soft, pour the ground masala from above step.
Include the cooked lentils, jaggery and water according to desired consistency. Bring it to boil, finally add sauted onions and salt. Switch off after a while.
Hotel style idli sambar is ready. Garnish with coriander leaves and relish with steamed idli, dosa.