Heat oil in a non-stick wok/kadhai over medium heat and once the oil heats up add mustard seeds. When the mustard seeds start spluttering, add onions, along with curry leaves, green chilies and peanuts.
Fry the onions for a minute or two and then add potatoes, salt, turmeric powder and sugar (if using). Mix well. Cover the wok and lower the heat to medium-low. Cook the potatoes for about 10 minutes or until done. Stir once to avoid sticking.
Add poha and lime juice. Mix well. Let it cook for about 5 minutes.
Take off heat. Garnish with coriander leaves and sev. Serve immediately.