Boil the potatoes and mash well. Heat the oil in a pan and add mustard seeds. When it starts to pop add cumin seeds and urad dhal and fry for few minutes. Then add the chopped onions, green chilies, garlic and fry until the onions turns golden. Add the mashed potatoes, turmeric powder & salt. Mix well and fry for 10-15 minutes by stirring constantly. Garnish with chopped cilantro leaves.