In a pressure cooker add the greens along with a cup of water and mix well, close the lid and cook for 3-4 whistles. Open the cooker only after the steam has been completely released.
Using a hand blender, blend the greens while gradually adding the maize flour. Keep aside.
in another pan heat the mustard oil, add in the grated ginger and garlic. Saute for a minute
Add in the chopped onions and saute until slightly brown. Add in the chopped green chillies. Mix well.
Add in the tomato puree, salt and cook for about 2 - 3 minutes
Add in the blended greens and mix well. Cover and cook for about. 2-3 minutes. Turn off the flame .
The saag is ready to be served with a dollop of white butter on top.