In a small mixer, grind the grated coconut and the green chilies until the chilies are well ground. If using frozen coconut, thaw the coconut before using.
I used my food processor to make the dough. you could also knead the dough using your hands.
Place both the flours, ground coconut / green chilies mixture, salt to taste and butter in the food processor bowl.
Run the food processor to combine all the ingredients. Now add the chopped onion and combine. Slowly add just enough water to make a stiff dough. Be careful when adding water as the coconut and onion has enough moisture.
Rest the dough for at least 30 minutes.
Heat a tawa / griddle in medium low heat.
Divide the dough into 12 equal pieces. Dust the dough with flour and then roll it into slightly thick circles.
Cook the roti in the hot pan. Use some coconut oil to brush the rotis and cook until the rotis are golden brown on both sides.
Remove and keep it warm until ready to serve.
I served the roti with some simple Dali Thoy / Vegan spiced lentil.