Pre-heat oven to 350 degrees Fahrenheit (177 degrees Celsius).
Cut a circle around the center of the base of the cauliflower to remove the florets (flowers). Once you have separated the large florets, further separate each floret into its tiny flowers. Cut the remaining pieces into paysanne cuts. It is essential to cut the cauliflower into small pieces to ensure they cook evenly compared to the eggplant and onions.
Dice the onion, cube the eggplant, finely chop flatleaf parsley, and roughly chop garlic. Set aside.
2. Toast and Grind Spices
Break open the cardamom pods with a mortar and pestle and remove the cardamom seeds.
Combine curry leaves, fenugreek seeds, cardamom seeds, ground cumin, brown mustard seeds, turmeric powder, ground nutmeg, red chili powder, and cloves in a mixing bowl.
Place a sauté pan on the stovetop at medium-low heat. Add spices and toast them for 30 seconds to 1 minute until intensely aromatic.
Pour spices into an electric spice or coffee grinder. You may also use a mortar and pestle. Grind ingredients.
3. Sauté Onions and Add Spices
Place a large oven-proof pan on the stovetop at medium heat. Once the butter melts, turn the heat on the stovetop down to medium-low. Add onions and garlic.
Cook for 10 minutes. Stir occasionally to ensure the onions do not stick.
Add ground spices, stir and, cook onions for an additional 10 minutes.
4. Coat Vegetables with Curry and Tomato Paste Mix
Add the cauliflower and eggplant. Stir.
Combine olive oil, Patak’s curry paste, and tomato paste in a mixing bowl and stir ingredients together.
Add Vadouvan curry powder and tomato paste mixture to the pot and coat vegetables with it. Sprinkle in salt and flatleaf parsley. Stir.
Cook the vegetables for an additional 5 minutes.
5. Cook in the Oven for 30 Minutes
Cover the oven-proof pan (or pour vegetables into an oven-proof casserole dish and cover with foil or lid) and place the pan in the oven.
Cook for 30 minutes or until the vegetables are tender.