1. In a woke, heat up a couple of tbsp oil, add cumin seeds, coriander seeds and mustard seeds.
2. When they crackle, add the chopped onions, ginger and garlic. Saute for a couple of minutes.
3. Add salt followed by turmeric and red chili powder, saute until onions turn slightly golden brown.
4. Add the chopped tomatoes, saute for about 2 - 3 minutes, until soft. Then, turn the heat off.
5. Add water, mix to combine . Transfer the mixture into another jar or bowl and using a hand blender, blend the mixture to get a coarse paste,
6. Pour the blended mixture back into the pan, add the Brussel sprouts, cover and let it simmer in the sauce for about 4 - 5 minutes until tender.
7. Serve over rice or with naan or any other Indian flat bread.