Heat enough oil for deep-frying in a kadhai or deep, heavy-based pan to 180°C / 350’F, or until a cube of bread browns in 30 seconds.
Working in batches, add the potatoes to the hot oil and deep-fry for 1-2 minutes, or until three-quarters cooked and light brown in colour. Remove with a slotted spoon and drain on kitchen paper (paper towels).
When cool, scoop out the center leaving a 5-mm / 1/4-inch gap from the sides.
For the filling, mix all the ingredients together in a bowl. Season with salt and stuff the scooped potatoes with the filling.
To make the chutney, put the coriander and mangoes in a blender or food processor and process to make a paste. Add the mint and process again to make a smooth paste.
To make the sauce, heat the ghee in a large, heavy-based pan over medium heat, add the cumin seeds, and stir-fry for about 1 minute, or until they start to splutter.
Add the pastes and stir-fry for 1-2 minutes, or until the moisture has evaporated. Now add the ground spices and a pinch of salt, then add the tomatoes and stir-fry for about 2-3 minutes, or until the moisture has evaporated.
Remove the pan from the heat, stir in the yoghurt, then return to low heat, add the potatoes and simmer gently for a few minutes until hot.4