Peel, wash, and cube potatoes. Place cubed potatoes in a saucepan, cover with cold water, add about a teaspoon of salt and bring to boil. Cook potatoes until just soft, about 7 minutes. Drain immediately and rinse with cold water.
In a small bowl, combine cumin powder, turmeric, cayenne pepper, and salt to taste with 2 tbsps water. Mix until a smooth paste forms.
In a skillet (well-seasoned cast-iron works best), heat vegetable oil. Add potatoes and fry until lightly browned. Remove the potatoes with a slotted spoon.
To the same skillet, add asafetida and cumin seeds. Cook until the cumin seeds begin to brown. Now return potatoes to the skillet.
Pour the spice paste made in step 2 over the potatoes. Continue cooking over medium heat for another 5 minutes.