1. Grind together the cubed onions, green chillies, ginger, and garlic to a smooth paste.
2. Add the melon seeds or cashew nuts and grind further to a smooth paste, adding a few spoonfuls of water.
3. Heat the ghee (or butter or oil) in a pan and add the cumin seeds.
4. When they splutter and turn fragrant, add the sliced onions and sauté until lightly browned.
5. Add the ground paste and tomato sauce (if using) to this and simmer for 3-4 mins.
6. Meanwhile, pick the leaves of the methi and wash well.
7. Chop roughly and add to the simmering paste along with the green peas.
8. Add the milk and some salt. Mix well.
9. Cook covered for about 10 mins until the peas is cooked soft.
10. Uncover and add the garam masala and more salt if needed.
11. Mix and remove from fire. If the gravy is too thick, add more water or milk and bring to boil again before removing from flame. If too watery, you can simmer it longer but remember that the gravy will thicken as it sits.