Cook the potatoes in salted boiling water for 15-20 minutes or until tender. Drain, peel and set aside.
Crush the mustard seeds in a small mixer ( or mortar & pestle if you have one) to a powder. Mince the chilli and add it to the mustard powder. Add the ghee, ginger and cilantro to the mixture and let it sit for a while until the potatoes cook and cool down. This will also help the flavors to blend together.
When the potatoes are cool enough to handle (but still warm) Mash them, then sprinkle with salt and the mustard mixture. Mix well and shape into little balls.
The authentic recipe uses only the regular potatoes. As a variation I tried the same recipe with exactly the same ingredients but with sweet potatoes. It turned out to be very unique! The sweet-salty-spicy combination was fantastic!
Serve them room temperature. It makes for a healthy and tasty snack. I personally love to eat them with ketchup.