Chop the onion (finely or thinly) and keep it aside.
Heat oil in a large pan and add the cumin seeds.
As the cumin seeds are lightly fried, add the ginger garlic paste, saute for few seconds.
Add the chopped onion and saute the onions for few minutes until the onions are lightly browned. Stir in between so the onions won't stick to the pan and they also get evenly cooked.
Once the onions are lightly browned, add the tomato sauce and mix well with the onions.
Saute for another one to two minutes while you stir constantly.
Add the spice powders - turmeric, coriander powder, red chili powder and garam masala powder, mix everything well with the onion tomato sauce mixture.
Also add the frozen green peas and enough salt to the pan, mix well with the contents and saute for another 1 minute.
Add the water, mix well with the onion tomato peas mixture, and bring the mixture to a boil.
Once the mixture starts to boil, cover the pan with lid, reduce the heat to low and cook for about 12 to 15 minutes until the onion tomato mixture & green peas are well cooked.
Make sure to cook until the green peas is soft enough and the gravy is also well cooked.
Meanwhile you may lightly stir fry the sliced paneer cubes in a little oil, if desired (you may also add fresh paneer instead of fried paneer).
Once the onion tomato and peas mixture is well cooked, add the paneer slices, mix with the gravy, cover and cook for another 2 minutes (make sure not to overcook the paneer).
Once it's done, add the kasoori methi, coconut cream or heavy cream and mix in with the prepared matar paneer or peas paneer. Also garnish with chopped cilantro leaves if desired.
Serve the easy and delicious matar paneer curry with rice or Indian breads like chapathi, poori, naan bread etc!