In a medium deep pan, add the oil and heat on medium.
Add in the mustard seeds and let them start to sputter.
Add in the fennel and mix for a few seconds.
Add in the leek and cook for 2 minutes.
Add turmeric and salt. Mix.
Add in the potatoes and mix well to coat spices.
Cook covered for 15-20 minutes on low heat until potatoes are well done. Stir 1-2 times in between.
Serve hot garnished with chopped cilantro or chopped green onion. Serve as part of meal with any lentil soup(Daal), or beans curry, Indian flat bread(Roti) and salad or any indian pickle. or as a side with any meal or as is.