Heat a small dry pan over low-medium heat. Add coriander seeds, cumin seeds, dried red chilies, and black peppercorns. Dry roast for 2-3 minutes, stirring constantly, until fragrant and slightly darker. Be careful not to burn them. Remove from heat and let cool completely.
Transfer the cooled spices to a spice grinder or mortar and pestle. Coarsely grind them. Set aside. This is your fresh Kadai Masala.
Heat oil in a large heavy-bottomed pan or Kadai over medium heat.
Add the cumin, nigella, and fennel seeds. Allow them to splutter for a few seconds. Next, add finely chopped onion and sauté until golden brown, about 6 – 8 minutes over low heat.
Add the ginger-garlic paste, tomato puree, turmeric, salt, chilli, and coriander powder. Cook for another 5 minutes or until until the oil starts to separate from the mixture (this indicates the tomatoes are cooked down).
Add the quartered mushrooms and vegetables to the gravy. Mix well and cook covered for 5 minutes. Mushrooms will release water and then start to absorb the flavours.
Add the ginger juliennes, kasuri methi, and half of the kadhai masala. Stir well.
Add coconut milk or cooking cream, cover the pan, and cook for 5 minutes, or until the vegetables are tender. You want them cooked but still retaining some bite.
Remove the lid. Add the remaining half of the freshly ground Kadai Masala. Cook for another 2-3 minutes, allowing the fresh spices to infuse the dish. The gravy should be semi-dry and cling to the mushrooms and vegetables. If it’s too dry, add another splash of water; if too wet, cook uncovered for a few more minutes until it thickens.
Garnish generously with fresh chopped coriander leaves.
Serve Kadai Mushroom Masala hot with naan, roti, paratha, or steamed basmati rice.
Notes
Adjust Spice Levels: The dried red chilies and peppercorns in the Kadai Masala are your primary heat source. Adjust their quantity based on your preference. You can also add more red chilli powder to the gravy if you like it spicier.