Keep couple of garlic cloves crushed with skin for tempering.
Soak tamarind in 1/4 cup of water and get the tamarind juice.
In a pressure cooker add pigeon pea, onion, tomato, green chili, garlic, turmeric powder, fenugreek seeds, cumin seeds, asafoetida powder. water as needed and cook for 5 whistle. Once the pressure is gone filter all the water from the dal and keep it aside.
Heat oil in a pan. Now add mustard seed. Once the mustard seeds stop splattering add dry chili, crushed garlic, curry leaves and sauté until garlic raw smell is gone.
Now remove only the dry chili from the tempering and add to dal and mash well.
Now add tamarind juice to tempering and bring to boil.
Now add the mashed dal and boil once.
Now add coriander leaves and remove from heat and serve.