In a bowl mix together potatoes, onions, green chillies, gram flour, semolina, cumin seeds, red chilli powder, coriander leaves, salt, yogurt and sufficient water and make a batter of desired consistency.
Let it rest for ten minutes. Heat a non stick tawa. Put two drops of oil and wipe the tawa clean with a wet muslin cloth so that the tawa is tempered.
Pour a tablespoon of oil on the tawa and pour half a ladleful of batter and spread it into a three inch round uttapam. Cook, turning sides, till golden brown on both the sides.
Serve hot with green chutney.