Prepare the Spice Paste: In a mortar and pestle (or mixer), crush the dry coconut, garlic cloves, ginger, and fresh coriander leaves into a coarse paste.
Temper the Spices: Heat oil in a deep pan or kadhai. Add the mustard seeds and let them pop. Then, add the cumin seeds, hing powder, and curry leaves.
Sauté the Onion: Add the finely chopped onion to the pan. Sauté it well until it turns a light golden brown colour.
Add the Masala Paste: Add the freshly crushed coconut-garlic paste into the pan. Stir and roast it nicely in the oil.
Cook the Tomato: Add the chopped tomato and salt to taste. Sauté for about a minute until the tomato softens.
Add Dry Spices: Lower the heat and add turmeric powder, garam masala, and Kanda Lasun Masala. Mix everything together to form a rich base.
Add the Dal: Drain the water from the soaked toor dal and add the dal to the pan. Sauté it in the spices for a minute.
Add the Drumsticks: Toss in the cut drumstick pieces and mix gently so they are coated well with the masala.
Add Warm Water: Pour in 1 glass of warm water and stir well. Add the second glass of warm water (adjust the water based on how thick or thin you want your gravy).
Simmer and Cook: Turn the flame to medium-low, cover the pan partially with a lid, and let it cook for 10 to 12 minutes.
Check for Doneness: Check if the dal and drumsticks are completely soft and cooked through. Serve hot!