Use your palms to gently smash the boiled and cooled potatoes. Smash them lightly until the shape is broken, but still holds well
Heat the oil over medium heat in a fry pan
Add the chopped chilli and a pinch of the cumin and quickly stir through the oil using a wooden spoon
Add the smashed potatoes to the pan and let them sit without stirring for a minute or so, until the skin crisps nicely. Flip the potatoes and continue to cook. Break the potatoes up gently, without mashing them up
Add the ginger, half of the coriander leaves, and all the spices to the pan and stir through the potatoes
Add the lime juice and continue to mix until the raw smell of the ginger and spices is gone
Serve in a hollow dish and top with spoons of the yogurt, chilli, the remaining coriander. Sprinkle over the chaat masala if you are using it. Serve fresh!