To make the sambar powder: First, heat 2 teaspoons oil and 1/2 teaspoon fenugreek seeds in a pan.
Lower the heat and add 1/2 teaspoon coriander seeds, 1 tablespoon cumin seeds, 1 teaspoon urad dal, and 1 teaspoon chana dal.
Roast the spices until golden brown.

Next, add 16-18 dried red chilies and some curry leaves. Roast until the chilies are crisp. Let the spices cool completely, then transfer to a blender with 1/4 teaspoon asafoetida. Blend into a slightly coarse powder. Your sambar powder is ready.

To make Idli Sambar: In a large pan, heat 2 teaspoons oil. Add 1 teaspoon mustard seeds, 1/4 teaspoon fenugreek seeds, a pinch of asafoetida, and a few curry leaves. Sauté for a few seconds.
Add 4 shallots and 2 green chilies. Sauté for 1 minute until the color changes.
Add 1 chopped tomato and continue to cook. Add the mixed vegetables and sauté for 2 minutes.

Sauté for 2 minutes, or until the vegetables start to soften. Add 1/2 teaspoon turmeric powder, 1/2 teaspoon jaggery, 1 teaspoon salt, and 1 cup water. Mix well, cover, and simmer for 10 minutes or until the vegetables are almost cooked. Add 3/4 cup tamarind extract and mix well. Cover and simmer for another 10 minutes, or until the raw smell of tamarind disappears. Add 1 cup cooked toor dal and mix well. Add water as needed to adjust the consistency and mix thoroughly.

Bring to a boil for 1 minute, or until bubbles appear. Add 4 tablespoons of the prepared sambar powder, or use store-bought sambar powder if preferred. Mix well, making sure there are no lumps. Boil for 1 minute, until the flavors are well absorbed. Add 2 tablespoons chopped cilantro and mix well. Finally, enjoy the hot idli sambar with freshly steamed idlis.