Mash the potatoes, add one fourth cup bread crumbs, sago, onion, salt, black pepper powder, coriander powder and chaat masala and mix well. Divide the potato mixture into twelve small balls, flatten them and stuff cheese in the centre and shape into tikkis. Coat the tikkis with the remaining bread crumbs.
Heat sufficient oil in a kadai and deep fry the tikkis till golden brown. Drain on absorbent paper.
Serve hot with tomato or green chutney.