Boil potatoes and dice them. Chop onions, garlic, ginger, coriander and the tomatoes. 2eat oil and sauté cumin seeds until they crackle. Add garlic and ginger and sauté until golden. Stir in chopped ginger and add the potatoes. Sprinkle turmeric and chilli powder and stir. Add tomatoes and simmer for about 5 minutes.