Chop onions. Heat mustard oil in a non-stick pan up to its smoking point. Cool slightly. Meanwhile, separate the cauliflower into big florets.
Heat oil again, add mustard seeds, cumin seeds, fenugreek seeds, fennel seeds, crushed cumin seeds, onion seeds and asafoetida and sauté till the seeds splutter.
Add onion and sauté till translucent. Add cauliflower florets, turmeric powder and salt. Chop green chillies and add. Sprinkle some water and toss to mix well.
Cover and cook on medium heat for a minute. Add ginger paste, garlic paste and yogurt. Mix well. Cover and cook till the cauliflower is done.
Serve hot, garnished with coriander sprigs.