Put a pot over low flame and add oil to it let it cook a little then add onions and cook until onion becomes transperent (do not over cook or brown onions)
Then add mustard seeds and cook for 1 min.
Then add sarson ka saag paste in there with garlic paste and cook for a while.Then add green chilli paste salt and red pepper powder in it.
Leave it over a low flame for abt 3 to 5 min to let all extra water evaporate.
In end put butter and simmer for futher 2 mins
It is ready to serve with makii ki roti and garlic chutni.