Heat oil in a pressure cooker or thick bottomed pan and add cumin seeds. After one minute or so when cumin seeds start spluttering, add chopped onion and saute for 4-5 minutes till onion become light brown in colour.
When onion are cooked add chopped tomatoes, turmeric, red chilli powder and cook till they are mashed. Now add 3-4 tablespoon of water and cook the masala for 5 minutes or till it stops sticking to bottom. If you are using cooked bhuna masala , you can skip above two steps and directly add ¾ cup bhuna masala paste.
Now add potatoes and shelled peas, cook for 5 more minutes and add coriander/cilantro leaves and mix them with the help of ladle.
Add two cups of water and cook till two whistles if you are cooking in pressure cooker or if you are cooking in normal pan cook it covered till potatoes are well cooked and tender generally that will take about 20 minutes on slow heat.
After opening pressure cooker add paneer cubes and cook further for 3-4 minutes.
If I am serving with rice I prefer this texture and when I am planning to serve it with poori or parantha I mash 7-8 cubes of potatoes with the help of ladle, and cook for 2-3 more minutes to achieve a thicker gravy.