To boil potatoes, place them into a large pot and cover with cold water so that the water is an inch above the potatoes. Cover the pot and bring to a boil, then lower the heat to medium. Test for doneness at 30 minutes. A sharp knife should easily go through the potato. Drain and set aside.
In a medium-sized pot, heat ghee over medium heat. Once it melts, add cumin seeds and mustard seeds.
When the cumin and mustard seeds begin to splutter, add the remaining spices.
Add the cooked potatoes to the pot and mix well, breaking them apart as you mix. Add the water to the pot. Raise the heat to high to bring the potato curry to a boil, then reduce the heat to medium and simmer for 5 minutes.
Add more water to adjust the curry to your desired consistency. Garnish with cilantro and serve.