Grind onion, green chillies into a coarse paste and keep aside. Take a bowl add bajra flour, ground paste and add remaining ingredients (except water)and mix together. Now add enough warm water and knead into a soft dough & divide into two balls.
Spread a wet cloth over a plate, now take a dough ball and flatten it in between your palms to make a round disc, then put it on wet cloth and make into roti by pressing with fingers. If needed, dip your fingers in water and continue pressing till the roti is as thin as you desire.
Heat a tawa, when hot place the roti carefully over the hot tawa and dry fry the bajra roti for 2 mins each side on medium flame till done. Now palak sajja roti is ready to serve, serve with fresh curd or pickle.