Boil potatoes in salted water to cover until tender, about for 7 minutes. Drain potatoes, return to hot pot to dry them out.
Heat skillet over medium high to high heat. Add cumin seeds. When seeds pop and crackle, add oil, then onion. Saute onion 2 minutes, stirring constantly. Add potatoes to the pan and toss to coat and lightly brown, about 3 minutes. Remove the pan from heat, season with salt, to taste, and serve.