In a large saucepan cook potatoes, covered, in enough boiling water to cover for 12 to 15 minutes or just until potatoes are tender. Drain potatoes in a colander; set aside.
Whisk together yogurt, salt, and pepper; set aside. Heat oil in the same large saucepan. Add cumin seeds and cayenne. Gently stir in potatoes. Cook and stir for 4 minutes. Remove from heat; gently stir in yogurt mixture and cilantro. Transfer to serving bowl. Serve warm or at room temperature. Makes 4 to 6 servings.