Boil potatoes until just tender, peel, and cut into bite-sized cubes.
Heat vegetable oil in a skillet, crackle mustard seeds, green chilies, and curry leaves.
Add ginger paste, turmeric powder, and cubed potatoes.
Sauté uncovered on medium heat for 10 minutes until potato edges turn golden and crisp.
Sprinkle black pepper powder and salt, toss for 1 minute, and serve warm.