Roughly chop the onions. Chop the green chillies and coriander leaves finely.
Dry roast the coriander seeds and cumin on low flame for one to two minutes till they turn aromatic.
Roughly crush the roasted coriander seeds and cumin in a pestle and mortar.
Now mix the crushed coriander and cumin seeds with the chopped onions, green chillies and coriander. Reserve half of this mixture separately which would be used for the topping while rolling the rotis.
Mix all the other ingredients mentioned above and add the remaining half of the onion mixture and mix well. Add water little by little and knead to a medium firm dough. Note that the onion might release some water too, so be careful not to add too much water while kneading the dough. Finally add 2 teaspoon of oil and knead well.
Cover this dough and let it rest for 20-30 minutes.
Now take a medium portion ball of this dough and dust with flour and roll slightly.
Place this roti over the reserved onion mix so that a good layer of onion is coated over the roti.
Dust the roti and roll it slightly more. Make sure not to roll the roti too thin and at the same time it should not be too thick too.
Now flip the roti with the onion side being down and apply a generous amount of water on the roti.
Heat a tawa or a cooker which is NOT non-stick and put the roti with the water-side being down so that it sticks to the tawa well.
Cook the roti on medium flame till you start seeing some bubbles or blisters on the roti. Do not apply any oil.
Now flip the tawa over the gas stove. Do not keep it over the flame directly, but just above the flame and cook for 30 seconds to 1 minute or till it is well cooked.
Remove the roti from the tawa and immediately grease with butter or ghee. Serve while it is hot.