1. Wash the brain thoroughly and boil them in water.
2. Remove the brains from the water and carefully remove any membrane or nerves.
3. Chop the brains into small pieces.
4. Heat oil in a stockpot and add onions.
5. Sauté the onions till they turn golden brown.
6. Remove half the onions and keep them aside.
7. Add green chilies, red chili powder, coriander powder, garam masala, salt, ginger paste, garlic paste and yogurt. Stir well and fry for about 10 minutes, adding a little water if required.
8. Add the brains and shake the pan gently to mix the brains with the spice mixture. Avoid stirring with a spoon.
9. When the oil separates from the spice masala, add chopped coriander, lemon juice, ginger and remaining brown onion set aside.
10. Serve hot with roti or naan.