The above facts are taken from wikipedia.
To make sarso ka saag You will need :
Sarso patta / mustard greens - 2 bunch
Spinach leaves - 1 bunch
Onions - 1 small, chopped
Tomato - 1 chopped
Jeera (cumin) - 1 tsp
Ajwain - 1/2 tsp
turmeric powder - 1tsp
garam masala - 1tsp
green chillies - 2 slit
milk - 1/2 cup
corn starch - 1/s tsp
Salt to taste
Lemon juice- 2-3 tsp
Firstly in a big pan mix both the chopped spinach and the chopped mustard greens, add a glass of water and cook covered until tender.Mash the greens with a hand blender and keep it aside.
In another pan, pour some oil and add the jeera and ajwain. once the jeera is light brown... add the onions and saute for 5- 10 minutes. Add the tomatoes and saute once again. Put one by one add all the masalas and keep stiring till thr raw smell of tomato is gone and the tomato is cooked well.
Now pour in the greens mixture and mix well... keep the gas on medium and cook. when the mixture reduces a bit add the milk to it and mix well and cook again. finally add the cornstarch mixed in some water to it and... off the gas after 5-6 minutes.
Top it with lemon juice and freshly chopped coriander leaves.
Serve hot with chapati, naan or rice. Enjoy!!