Wash the poha in a colander. Poha should be moist, but not mashed. Heat oil in a pan. Add mustard seeds, cumin seeds, curry leaves and onions, and green peas. Saute. Add tomatoes. Saute. Add green chilies and turmeric power and mix. Add potato (boiled and cut into 1 inch pieces) and poha. Mix and cook until poha is heated through. Add lemon juice and mix lightly.
Garnish with coriander leaves and serve hot.