Add ginger-garlic paste, turmeric powder, red chilli powder, dhania powder, garam masala powder, salt, jeera powder, 1/4 cup chopped coriander and mix well. Let the masalas coat the potatoes, keep a side for 10 mins.
Heat oil in a kadai. Add cumin and mustard seeds. When it starts crackling, add curry leaves and the potatoes.
Keep sauteing it occasionally. When potatoes are 3/4 done, add curds and let it cook for 4-5 mins till the potatoes are cooked.
Garnish with chopped coriander and serve with parathas or rice.