Heat the mustard oil in a heavy-bottomed kadhai until it reaches its smoking point. Add the potato wedges and fry them over medium heat until they are golden brown and crisp on the outside. Remove them and set aside. Similarly, fry the dal wadi (if adding) till golden and transfer to a bowl.
In the same kadhai (with the remaining oil), add the cumin, asafoetida, and dried red chilli. Saute for a few seconds. Add the coarse pea paste and chopped tomatoes. Sauté the paste over medium-low heat, stirring continuously for 7-10 minutes. Add the spices, salt, and mix nicely.
Pour in the hot water to achieve your desired consistency. Simmer on low heat for 8-10 minutes.
Add the green masala paste, and the leftover ¼th green peas. Mix well. Cook for 2-3 minutes. Then add the fried potatoes, and wadi.
Cover the kadhai and let the nimona simmer over low heat. This allows the potatoes, whole green peas to finish cooking and all the flavors to meld.
Serve matar ka nimona hot, garnished with a generous drizzle of ghee and chopped coriander leaves.