Take potato pieces and fry them in pan (take oil accordingly, heat the oil first then put the potatoes into it) till it turn light reddish in color. Take the potato pieces out of the pan. Now take out the oil from the pan. Add few amount of oil in the pan such that tomato puree can absorb that. Heat the oil. Now add hing in the oil. Make a paste of turmeric, chilli and coriander powder by adding few amount of water. Add that paste in the heated oil. Now after few seconds add tomato puree into it. Fry the puree in the oil till oil oozes out. When oil is oozing, then add potatoes and salt (according to taste). Fry them for few minutes.