Spicy Potato Filling

Potatoes are used in wonderfully imaginative and satisfying ways all over the Subcontinent. Many simple potato dishes begin, as this recipe does, with potatoes boiled in their skins, which are then peeled, chopped or crumbled, and cooked with some oil and spices or herbs in an infinite number of variants (see Tamarind Potatoes, and Parsi Potatoes and Snow Peas, for example). You can begin with potatoes you boiled a day or