Its a famous bengali dish made with potato and parwal goes really well with roti and is a great tiffin lunch.
In a pan, heat 2 tsp mustard oil.
Add 1/4th tsp kalonji, 1/2 tsp of chopped garlic, 1 tbsp each of julienned onion and chopped potato, 2 tbsp diced parwal, 1/4th tsp each of haldi and red chilly powder and 1/8th salt.
Mix well, add water and mix again.
Cover and cook well.
Serve hot with chapatti.