Peel and cube the potatoes into roughly half inch cubes. Cover with water and cook in microwave for 5-6 minutes. Drain.
Heat oil in a pan. When oil is smoking add mustard seeds and allow to splatter. (Keep covered.) Then add chopped onions, chillies and coriander leaves. Fry till onions turn transparent. Add ginger and garlic paste, turmeric and stir for 1-2 minutes. Add potatoes and salt to taste. Cover and cook for 5-6 minutes, stirring once or twice. Add tomatoes and peas and cook for a few more minutes, till peas are soft. Mix well.
Serve hot with chapatis/ parathas or other flat bread.