Prep the Cauliflower: Cut the cauliflower into small florets. Soak them in a bowl of hot water with 1/2 teaspoon turmeric and a pinch of salt. Do not boil the water with the cauliflower in it; just let it rest in the hot water to thoroughly clean it and remove any impurities.
Heat the Oil: Place a kadai on the stove and heat 1, 1/2 tablespoons of oil.
Temper the Spices: Once the oil is hot, add mustard seeds, cumin seeds, asafoetida (hing), and curry leaves. Let them splutter.
Sauté the Onion: Add the finely chopped onion and roast it on medium heat until it turns soft and slightly golden.
Add the Green Paste: Stir in the fresh ginger-garlic-green chilli-coriander paste and sauté well until the raw smell goes away.
Cook the Tomatoes: Add the chopped tomato and salt to taste. Cook for about a minute until the tomato softens.
Add Dry Masalas: Lower the heat. Add the cumin-coriander powder, garam masala, and Kanda Lasun Masala. Sauté the spices for a minute.
Add Cauliflower: Drain the cauliflower florets from the hot water and add them directly to the spiced mixture in the kadai. Toss well on medium heat so every piece is coated with the masala.
Steam Cook: Turn the heat down to low and cover the kadai with a tight lid. Let the vegetable steam-cook in its own moisture for 5 to 7 minutes. Open the lid once to stir, then cover again for another 3 to 4 minutes until the cauliflower is completely tender.