Boil the potatoes until soft but not mushy. Peel them and chop into cubes. If you are using the microwave, peel them and chop into cubes. Place in a microwaveable bowl with a quarter cup of water, cover and cook on high for 5 minutes or until soft
Heat oil on medium heat. Add mustard seeds
Once the seeds start to splutter add the onion and curry leaf and sauté until onions are slightly brown
Add ginger and garlic paste and sauté for another minute
Add the ground coriander, cumin, turmeric and chilli powder (you can use 1 or 2 teaspoons, depending on how much heat you want) and fry for a minute. Add a few drops of water if required
Add the potatoes and the vegetable stock and cook for 2 minutes or until the stock starts to thicken and potatoes are soft and tender. Season with salt only if required as the salt from the stock may be sufficient
Add the garam masala and chopped coriander. Mix well and remove from heat
Serve hot