Heat oil in a large pan on medium heat. Add mustard seeds and once they start popping, add green chilies, curry leaves and onions. Cook on medium heat until the onions turn translucent, about 4~5 minutes. Add ginger+garlic paste and cook for another 1 minute. Next add in the tomato paste and cook for 1~2 minutes.
Stir in tomato puree, spices and cook till the mixture starts to simmer.
Add the chopped spinach and cook till wilted, about 3~4 minutes. Stir in the beans and paneer. Add enough water to get to desired consistency. Season with salt and cook covered for the flavors to mingle, about 6~8 minutes.
Finally add heavy cream, if using, and cook till heated through, about 1~2 minutes. Turn off the heat, cover and set aside for at least 10 minutes before serving. Serve with roti or rice.