In a bowl mix whole wheat flour, soya flour, jowar flour, bajra flour and salt. Add green chillies, onion, coriander leaves, turmeric powder and mix. Add enough water and knead into a soft dough. Rest the dough for ten minutes.
Divide the dough into twelve equal portions. Dust with flour and roll out into medium thick chapattis.
Heat a tawa and roast the chapattis till done on both sides.