500g/1lb 2oz cooked chickpeas, cooking liquor reserved (chickpeas should be soaked overnight in water, drained, covered with fresh water and cooked for two hours until tender then cooled in their cooking liquor)
To make the spiced chickpeas, drain the chick peas, reserving the cooking liquor.
Heat the vegetable oil in a saucepan until hot then add the mustard seeds and salt and cook for a minute or so until the mustard seeds start to pop. Add the chili powder, shredded root ginger, chickpeas, tomatoes and a good handful of curry leaves. Cook until the tomatoes start to break down. Add 200ml/7fl oz of the reserved cooking liquor from the chickpeas. Allow to cook, topping up with more cooking liquor if it becomes too dry.
For the potato cakes, remove the potato flesh from their skins. Allow to cool a little (if hot). Put two thirds of the potato flesh into one bowl and the other third into another bowl. Add the flour to the larger amount. To the smaller amount add the salt, garam masala, red chilli and coriander leaves. Mix both well.
Divide the flour and potato mix into 110g/4oz balls and flatten out into rounds using floured hands. Squeeze the seasoned mix together and make into 55g/2oz balls. Place a ball into the center of each flattened round of potato and wrap around so that the ball is encased completely.
In a large frying pan, heat the vegetable oil until hot. Shallow fry the potato cakes on all sides until brown and crisp. Drain on kitchen paper.
Finish the chickpeas with some coriander and curry leaves. Serve with the potato cakes.