Wash the potatoes and cut them into two halves and then start cutting them vertically.
Take a vessel and add some water to it. Now add the sliced potatoes and keep them for boiling in an open container. The potatoes while boiling should not be totally cooked, they should be cooked partially.
When the potatoes are partially boiled, drain away the water and wash it again with cold water. You can remove the peels if you wish to.
Take a container and keep the potatoes in it, add salt, red chilly powder, cumin powder, chaat masala, chopped corriander, chilly flakes, oregano and cornflour to it. Mix the mixture well by adding 3-4 drops of water.
Keep the mixture aside for around 15 minutes. You could also refrigerate it for 20 mins.
Take oil in a pan and heat it. Once heated properly, deep fry the potato slices covered with spices. Once fried squeeze a lemon and some chaat masala and serve hot with tomato ketchup or green chutneys.
Refrigeration of mixture helps the spices to stick to the potato slices. Additionally you can use herbs like mint as per your taste.