Boil the potatoes, drain and leave them aside for some time to cool. Hang the yogurt in a muslin cloth for some time till all the excess water drains out. Take it out in a bowl and add little salt and pepper powder. Beat lightly. Peel the potatoes and cut them in dices.
Heat oil in a medium pan over a medium heat. Add the potatoes with little salt, red chilli powder. Stir and cook the potatoes for few minutes. Take the pan off the heat and allow the potatoes to cool.Transfer the potatoes into a serving bowl along with the oil and the seasoning. Add the yogurt and mix.
Serve garnished with chopped coriander leaves.